RELNOTES

                                    TXR 298
                                   2024-12-17


  Bugs

  - listener: regression: txr won't start interactively
    if ~/.txr-profile or ~/.txr_profile file is not present,
    terminating with an error about nil being passed to abs-path-p.



                                    TXR 297
                                   2024-12-16


  Features

  - Lib:
    - mapcar now has a synonym, map.
    - copy: now handles range objects.

  - Listener
    - TXR now looks for .txr-profile and .txr-history files
      with a dash; if those are not found, then it falls back on
      trying .txr_profile and .txr_history (and will save the
      history to the legacy name).

  Bugs

  - regex:
    - regression in read-until-match and related function
    - flaw in NFA state machine such that the new REGM_MATCH_DONE
      state is not taken advantage of and we still read more
      characters than necessary to match certain regexes.
  - ffi: size calculation for structures with a flexible array
    member is now done in the modern way, not the C99 way that
    was changed by a defect report.
  - string ranges:
    - iteration of string ranges whose endpoints are identical strings
      was wrongly producing an empty sequence rather than a sequence
      of length 1 containing that string.
    - length of reversed string ranges produced incorrect results
      on some platforms
  - assembler warning on loongarch64.



                                    TXR 296
                                   2024-08-07

                         Fifteenth Anniversary Edition


  Features

  - Lib:
    - new cshuffle, cnshuffle functions which output cyclic permutations

  - sequences:
    - new wheref, whereq, whereql and wherequal functions:
      companions to where.
    - new functions find-maxes and find-mins: find multiple minimal/maximal
      elements.
    - new mapfun argument in keep-if, remove-if and keep-keys-if, allowing
      output to be mapped through function.
    - zip, transpose: more permissive; will not fail when trying to
      produce strings, but a non-character object occurs.
    - seq-like: new function which makes a sequence out of its second
      and subsequent arguments which is of the same kind, if possible,
      as its first argument.

  - OOP:
    - structs can now have special methods slot and slot-set
      and special functions static-slot and static-slot set
      - these dynamically handle the case when a slot is not found.

  - JSON:
    - JSON printing now renders struct objects.
    - A "__type" property is emitted, giving the type.
      - can be disabled by making *print-json-type* nil.
    - new *read-json-int* variable
      - controls whether JSON integers are read as integer objects or float.
      - integers are defined as numbers without a decimal point, e or E.

  Bugs

  - TXR Pattern Language:
    - spurious retention problem solved
    - allows, e.g. @(repeat) through huge files without runaway memory.

  - regex:
    - the read-until-match function now avoids all unnecessary consumption
      of input.
      - this means that if data is being delimited by regex out of
        a real-time source such as a socket, it will not hang waiting
        for more input that is not yet available, even though the
        record has already been delimited.
      - GNU Awk's record separation has similar issues.

  - hash tables:
    - hash codes of struct instances and hash table objects being
      wrongly reduced into positive fixnum range instead of using the
      full pointer-sized unsigned type.
      - forgotten change not made six years ago.

  - JSON:
    - flat-p argument in put-json and put-jsons now works correctly;
      no stray newlines are emitted.

  - sequences:
    - sub function was returning an iterator in some cases resulting
      in odd results like:
      (partition 1..10 '(2 3)) -> ((1 2) (3) #<seq-iter: a24c380>)
    - partition, split and split*
      - infinite looping regression
      - handling of negative indices (that are still negative after
        subtracting length).
    - split, split*: poor behavior for indices beyond length



                                    TXR 295
                                   2024-06-28


  Features:

  - TXR Pattern language:
    - Promising solution found for spurious retention problem that has
      plagued the project from nearly its beginning!
      - Fix allows large files to be scanned without consuming more
        and more memory.

  - Lazy lists:
    - New function lcons-force: recursively force.

  - Printer:
    - pprint prints buf objects as hexadecimal, rather than dumping
      raw bytes.

  - Quasistrings:
    - Buffer objects interpolated into quasistrings now appear in hex as
      contiguous digits, rather than as space-separated decimal numbers.
    - Buffer and string values now support separation:
      - if var is a string @{var ":"} will interpose : between
        the characters.
      - if it is a buffer, : will be interposed between pairs of
        hex digits, not individual digits.

  - Subprocesses:
    - New functions for filtering data through external processes:
      - map-command-lines, map-process-lines
      - map-command-str, map-process-str
      - map-command-buf, map-process-buf
    - New mode option supported by open-process and related functions:
      - mode syntax ?num, where num is a decimal number, specifies
        an alternative file descriptor to be used as the data source
        or sink by the returned stream.

  - Structural Pattern Matching:
    - new @(scan-all <pat>) pattern: like @(scan <pat>) but
      gets all matches.

  - Sequence iteration:
    - New iter-cat function for mapping over multiple sequences as one.
    - New copy-iter function to duplicate an iterator, at its current
      iteration point, so the original and copy independently walk
      the rest of the sequence.
    - iter-begin and related functions now recognize floating-point
      numbers and work with them directly, just like with integers,
      rather than returning an opaque, stateful iterator object.

  - Hash tables:
    - New function copy-hash-iter.

  - Combinations/Permutations:
    - New functions permi, rpermi, combi and rcombi which
      are like their counterparts without "i", but produce iterators
      rather than lazy lists.

  - Compiler:
    - Update list of effect-free functions.

  - Sequences:
    - interpose function uses seq_iter and seq_build.
    - length can now measure a string range like "AA".."ZZ".
    - string ranges are no longer ascending or descending,
      the individual characters are.
      - Thus ranges like "AC".."CA" work: the left letter
        counts up, the rightmost one counts down.

  - Lib:
    - lot of functions that were throwing exceptions of type
      error now throw more specific type.

  Bugs

  - gc:
    - inadequate marking in some iterator types.
    - protect the symbols used for cobj_class registration.
    - quantile: missing run-time type check for the state object,
      being of the expected type.



                                    TXR 294
                                   2024-03-17


  Features

  - Compiler:
    - Now generates inline code for chained functions and lambdas, such
      as that arising out of the opip syntax.

  - OOP:
    - new special method length-< lets a lazy sequence object implement support
      for being tested with the length-< function (is the length less than a
      given integer without forcing existence).

  - Lib:
    - New hist-sort-by function: hist-sort with a mapping function.
    - New functions cons-count and cons-find.
    - New function rangeref for obtaining an intermediate value from
      a range using an integer index as if it were a sequence.
      - For consistency: because ranges can be treated as sequences.

  - Pattern matching:
    - End pattern in @(sme) and @(end) can be any pattern now, not
      a list pattern.

  - Internals:
    - New framework introduced for gathering items into a sequence,
      called "seq_iter".
      - Takes into account the type of sequence being constructed up-front,
        to avoid the overhead of collecting a list and then coercing it.
    - Functions that have been improved with seq_build and in some
      cases seq_iter: keep-keys-if, separate, separate-keys, tuples, mapcar,
      mappend, mapdo, partition-by, partition-if, partition, split, split*,
      zip, unique, find, rfind, window-map, append, nconc.

  Bugs

  - stability:
    - gc problem in iter-begin.
    - gc problem in sub-str on lazy string arg.
    - gc issue in eval in code related to binding special variables.
    - gc correctness issues in make-strlist-input-stream,
      make-struct, make-lazy-struct, copy-search-tree,
      make-similar-tree, copy-fun (for VM functions).
  - build:
    - fix in configure script for BSD grep.
    - fixes in ordering issues in compilation of stdlib to actually achieve the
      shortest bootstrapping time.
  - ports:
    - fixes for OpenBSD.
    - Support PPC64 with Altivec more properly by saving and restoring
      VR31 register. Fixes a reported failure to build and pass tests.
      - Not a perfect fix: pragmatic whack-a-mole approach based on
        empirically seeing which Altivec registers occur in the code,
        needing saving.
    - cygwin:
      - fixed broken handling of drive-relative paths.
      - handling of termination status in run and sh functions fixed
        to be like that on POSIX platforms.
  - documentation:
    - source parameter of mmap documented.
  - mmap: too low length confusingly diagnosed: as "zero-sized element type".
  - hash-eql: always returning zero due to regression.
  - mapcar, mappend, mapdo: avoid alloca request proportional to number of
    args, switching to malloc over a certain size.
  - list-vec: accidental use of int type to hold vector length: fail on
    64 bit systems with vectors having more than 4G entries.
  - misc:
    - avoid realloc to size zero, since latest ISO C draft makes
      it undefined behavior.
    - keep-if: don't report as remove-if in errors.



                                    TXR 293
                                   2023-12-28


  Features

  - load:
    - when a top-level load exits by returning from the load block, the block
      value now becomes termination status of process.

  - JSON:
    - now supports Lisp comments as an extension.

  - I/O:
    - New functions read-objects, file-get-objects, file-put-objects,
      file-append-objects.

  - Hash Tables:
    - New function hash-join, similar to hash-uni but usefully different.

  Bugs

  - TXR: bug in @{nil ...} variable match.
  - compiler:
    - compile-file can now handle top-level forms that
      perpetrate a non-local exit, without requiring compile-only
      around them.
    - optimizer now watches for exceptions during constant folding,
      similarly to how the front end does.
  - listener:
    - several bugs in auto compound expr mode fixed.
  - perm, rperm, comb, rcomb functions:
    - now support all sequence types, not only lists, vectors and strings.
    - comb was skipping combinations: defective function repaired.
  - glob:
    - suppress duplicates generated when multiple double
      star patterns are present (supported by the recent glob*).
    - fix memory leak that can happen on early exit due to error
      function performing a nonlocal control transfer.
  - sh-esc family of functions (recently introduced):
    - incorrect specifications overhauled.
  - (rcons ...) print/read consistency issue fixed.
  - Cygwin: termination status returned by (sh ...) and (run ...)
    now has the correct integer value, or nil for abnormal exit,
    like on Linux.



                                    TXR 292
                                   2023-11-20


  Features

  - Build:
    - speed up compilation of stdlib with optimal compilation
      order of several key files.
    - Revised confusing build instructions in ./configure script.
    - Makefile improvements:
      - cruft removed; dependency generation simplified.
      - mkdir invocations factored out to rule.
      - DELETE_ON_ERROR: used now.

  - Streams:
    - A new protocol between the close-stream function and its
      lower-level implementation allows delegate streams to
      implement a reference counting discipline for closing.
    - open-file now supports a "T" mode for O_TMPFILE (on Linux,
      or anywhere else O_TMPFILE is supported).

  - Sequences:
    - New functions nested-vec and nested-vec-of for easily
      constructing (simulated) multi-dimensional arrays.
    - New mref accessor for multi-dimensional access.
      - also has a side job calling curried functions.
    - New csort-group function:
      - Like sort-group, but uses csort instead of sort for key caching.
    - New hist-sort function: make histogram of sequence, and sort
      by descending frequency.
    - New length-list-< function  for testing whether a list is
      shorter than a given length without traversing it beyond
      that length.
    - New length-< function for testing any sequence's length
      against a value without traversing/forcing the sequence
      to calculate its length.
    - ref now documented as accessor, not just function.
    - del operator now allowed on places that index into sequences
      implemented by structures:
      - requires both lambda and lambda-set methods.

  - Strings:
    - New str-esc function for generic character escaping.
    - New shell escaping functions: sh-esc, sh-esc-all, sh-esc-dq
      and sh-esc-sq.

  - Packages
    - New feature: local symbol renaming
      - Symbols can be imported under alternative names.
      - New use-sym-as function and :use-syms-as defpackage clause.
      - Better idea than nicknaming packages (package-local nicknames).

  - Functional library:
    - New: left-inserting pipeline operators: lflow, lopip, loand.
    - New: macros orf and lorf for condensing certain op syntax.
    - New: tap macro, for expressing side effects in pipelines while passing
      through the value.

  - Syntactic places:
    - New: ensure macro evaluates an expression and stores its value
      into a place, if that place's current value is nil.

  - Pattern matching:
    - some match-case instances are now transformed into casequal.

  - FFI:
    - Now provides a setjmp macro, longjmp function as well
      as a jmp-buf utility function that allocates a jmp-buf.
    - Now possible to interact with libraries that use longjmp
      for error aborts like libpng and such.

  - POSIX:
    - chdir function takes stream or file descriptor, which are
      handled via fchdir.
    - New glob* function to complement glob:
      - glob* supports the ** (double star) operator for recursing,
        via its own implementation, not relying on glob providing that.
      - glob* has its own implementation of brace expansion.
    - New rlink function which is like link, but resolves the target path
      if it denotes a symlink.

  - Listener:
    - *listener-sel-inclusive-p* is now default, since most terminals
      have block cursors by default.
    - New feature: auto compound expression mode lets you omit
      the parentheses.

  - Math:
    - The tofloat and toint functions are now generic via the
      user-defined arithmetic struct mechanism.

  - JSON:
    - Allow integer objects to be printed rather than insisting on
      numbers being floating-point.
    - Allow lists (including lazy lists) to print as [ ... ]
      rather than insisting on vectors.

  - Windows Installer:
    - Does not require admin privileges any more; will install for
      just the current user if the user isn't admin.

  - Documentation:
    - big change: new hashing scheme for navigation and doc lookup.
    - section titles now hashed in a more robust way that is resistant
      against most kinds of edits.
    - stdlib/doc-syms.tl file is now gone: one less thing to maintain.
    - Numerous fixes in manual.

  Bugs

  - Compiler:
    - numbers now externalized sanely in .tlo files:
      - compile-file makes sure base 10 is used for integers
      - floating point numbers written with sufficient precision

  - Loading:
    - load-args-process bugfix: :compile action must load.

  - Streams:
    - close-stream caches only successful result from underlying
      function.
    - a few close functions underneath close-stream were returning
      nil in the successful case.

  - OOP:
    - Fix segfault looking up special method after the static slots
      table of the type has been resized.

  - Pattern matching:
    - Missing autoloads for match-error and sys:match-pat-error,
      causing compiled files containing pattern matching not to load.

  - Awk macro:
    - prn returns nil

  - Search trees:
    - bug: tree-delete-specific-node not using key fun.

  - Lib:
    - Two bugs in flatten* function.
    - Bug in deletion of (ref ...) place: incorrect when object is list.

  - Crypt:
    - less strict error token detection for wider platform support.

  - Time:
    - time-utc and time-local methods must subtract gmtime, not add.
    - time-parse-utc and time-parse-local, likewise.

  - Build:
    - Misspelled PLATFORM_LDLIBS corrected.
    - Fix for _TIME_BITS being tied to _FILE_OFFSET_BITS
    - Address autoload circular dependency involving stdlib/error.tl
      that can fail builds under some library build orders.

  - Vim:
    - Fix lack of recognition for char escapes in quasilit.



                                    TXR 291
                                   2023-08-06


  Features

  - opip macro:
    - now supports binding variables which are visible
      to the rest of the chain.


  Bugs

  - symbol-function accessor: not supporting functions whose names are not
    symbols, like (meth ...)
    - Regression introduced in TXR 290.
  - compiler: invalid constant folding of load-time values.
    - Recent regression.
  - Pattern Language: in output-side @(repeat), inability to specify :vars
    together with :counter.
    - Regression dating back to March 2016.



                                    TXR 290
                                   2023-07-29


  Features

  - Compiler:
    - Deeper constant-folding optimizations, assisted
      by data flow information.

  - Data Integrity:
    - SHA-1 digest now provided; it is in wide use.

  - Lib:
    - group-by, group-reduce and unique functions refactored to use sequence
      iteration.

  - Math:
    - Numerous C99 math functions now exposed:
      - cbrt, erf, erfc, exp10, exp2, expm1, gamma, j0, j1, lgamma,
        log1p, logb, nearbyint, rint, significand, tgamma, y0, y1,
        copysign, drem, fdim, fmax, fmin, hypot, jn, ldexp, nextafter,
        remainder, scalb, scalbln, and yn
    - All of these can be user-defined in a custom arithmetic struct.

  - Environments
    - Internal representation of top-level environments is simplified,
      eliminating a level of indirection.
    - New functions for lexical introspection:
      - lexical-binding-kind, lexical-fun-binding-kind,
        lexical-symacro-p and lexical-macro-p.

  Bugs

  - hash: out-of-bounds access in hash-iter-peek function causing instability
    in hash iteration that depend on this function.
  - crypt function:
    - handle libxcrypt failure tokens properly, so that we treat them as an
      error instead of returnig them to the application.
  - md5: was totally broken on big endian.
  - VM: compiled functions were not picking up redefinitions of functions that
    they call, sticking with the old functions. This issue was uncovered during
    work on the new representation of top-level environments, which also
    happens to fix the problem.
  - pattern matching:
    - the above VM bug fix means that the double definition of
      sys:non-triv-pat-p in the pattern matching module is handled right;
      causing sys:transform-qquote to be expanded using the correct definition
      of the function, exposing an obscure issue with quasiquoted hash
      literals.
    - another bug: variable patterns like @var were not seeing lexical
      symbol macros, only global symbol macros, global variables and
      lexical variables.
  - environments: redefinition of symbol macros was found not to trigger cache
    invalidation in VM descriptors, causing compiled code to keep seeing
    the old definitions of the symbol.
  - lib: the del operator now works with index lists, which is the access
    notation like [obj '(1 2 4)] for picking out indices.
    As a result of this, there is a change in semantics in how the
    replace function handles index lists. If there are fewer replacement
    items than indices, then instead of stopping, the replace function
    deletes the specified indices. (Subject to -C option.)
  - paths: rel-path function was considering empty strings to be
    absolute paths, causing (rel-path "" "a") to be diagnosed as an
    invalid mixture of absolute and relative paths.
  - environments: bugfix in lexical-var-p and lexical-lisp1-binding.



                                    TXR 289
                                   2023-07-02


  Features

  - TXR Pattern Language:
    - New @(push) directive uses @(output) syntax to push lines
      back into input.

  - Pattern Matching:
    - New match-cond macro.

  - Lib:
    - New cached sorting functions, for situations when a fairly expensive
      keyfun is used for sorting.

  - Lisp:
    - eval takes macro environment.
    - integers and ranges are function-callable objects
      - provides succinct indexed access in functional expressions, using
        integers and ranges as higher-order functions.

  - Hash Tables:
    - Switched from chained hashing to open-addressing with linear probing.
    - New hash-map function: populate a hash with keys from a sequence, and
      values from a function over those keys.

  Bugs

  - hash tables: bug in initial hash mask calculation, caused zero bits,
    causing some chains not to be used, reducing efficiency.

  - gc bug in vector case of ssort function, causing crash.

  - equal: fix broken cases in equality substitution.

  - range objects were not treated as iterable in some situations,
    for no good reason: e.g. (take 13 "AA".."BB") didn't work,
    requiring (take 13 (list-seq "AA".."BB")) as a workaround.



                                    TXR 288
                                   2023-06-10


  Features

  - Lib:
    - New keep-keys-if, separate-keys functions.

  - Compiler:
    - New clean-file function for removing compiled file
      with name built-in path resolution strategy
      harmonizing with compile-file.
    - New compiler option log-level.
      - level 1: info message when file is compiled.
      - level 2: info message when top-level form is compiled.

   - Modularization:
     - New functions load-args-recurse and load-args-process
       - Handle a build/load command passed in *load-args*.
     - Provide a disciplined way to structure programs
       into hierarchical library modules.

  Bugs

  - Obscure in bug in compile-file giving rise to a .tlo
    that cannot be loaded, under certain conditions.

  - Autoload issue affecting with-compilation-unit,
    causing compiled files that use with-compilation-unit
    not to load.



                                    TXR 287
                                   2023-06-03


  Features:

  - Lisp:
    - New: progv special operator, similar to Common Lisp's

    - New: compiler-let: binds dynamic variables in the
      compiler's context, allowing control over the compiler
      at the expression level.
      - with-compile-options now implemented using compiler-let.

   - Awk macro:
     - redirection operators visible in wider scope
     - new :fun clause for binding functions local to macro.

   - Compiler:
     - small optimizations: when all local functions in
       a labels/flet block are unused, the frame is not
       generated for them.

   - Expander:
      - Parameter list macros now work in nested lambda lists.
        (This is also listed below under Bugs.)
      - New expander-let macro for binding special variables
        at macro-expansion time.
        - Allows customization of macros which occur inside,
          by having them respond to the values of the specials.
        - Used in TL-WHO port of CL-WHO to fix CL-WHO bugs.

   - Command line:
     - The -e option evaluates multiple expressions from
       the same argument string.
       - They are read together before evaluation, almost
         as if they were in the same progn.

   - Listener:
     - Evaluates multiple expressions in command line,
       instead of complaining about trailing material.

   - Lib:
     - load function has new features:
       - extra arguments may be passed to load, which are
         dynamically bound to a special var called *load-args*
       - a loaded file can bail early using using
         (return-from load) or (return-from load <value>)
       - the interrupted load function will then return that
         value to its caller.
       - thus loaded files can behave like functions with
         arguments and return values.

  Bugs

  - Android: fixes for running on Android 13 via Termux.

  - Environments:
    - Fixed crash when certain built in variables are removed
      with makunbound.
    - Fixed (symbol-value ...) wrongly storing a value to the
      top-level binding rather than the current dynamic binding.
    - Fixed bug in the VM: getlx and setlx instructions
      using dynamic lookup rather than global.

  - Expander:
    - Fixed bug in empty case of flets/labels causing
      unrelated symbol macros to be strangely affected.
    - Parameter list macros now work in nested lambda lists.

  - Awk macro: fixed completely broken redirection operators.

  - Parser:
    - There is now a proper handler for fatal Flex errors, like
      when a token is ridiculously long.
      - Flex-generated default handler prints something and exits.
      - Our handler throws exception.



                                    TXR 286
                                   2023-05-07


  Features

  - Hash tables:
    - some internal code improvements/streamlining
    - new hash-props function from instantiating a table from
      alternating key/value arguments, requiring no temporary
      list to be consed up.

  - Sorting:
    - New ssort and snsort functions: these are counterparts
      of sort and nsort which are stable on vector-like
      sequences.
    - The nsort and sort function's quicksort
      implementation now uses the Hoare partitioning
      scheme instead of Lomuto:
      - Observed a 21% improvement sorting a randomized
        vector of a million items.
      - The quadratic behavior on a sequence consisting
        of a repeated item is gone.

  - Time:
    - New time-str-local and time-str-utc functions, which
      reverse the arguments, for better
      partial application.
    - the time argument in time-{fields,struct}-{local,utc} is
      now optional; if omitted, the current time is used as if
      by calling (time).

  - Structs:
    - Small improvement in defstruct: if boa arguments are
      defined referencing slots that don't exist in any
      struct, this is now diagnosed.

  - Compiler:
    - Lots of new optimization work. There is now one more
      optimization round, and *opt-level* now goes up to 6
      rather than 7, 7 being the new default value. This
      release makes 23 compiler commits.

  Bugs

  - Fixed incorrect scope in conda/condlet.
  - Fixes for regressions preventing the source code of of
    stdlib/ being used (.tl files, not .tlo), which is needed
    for debugging some TXR problems.
    - Fixed issue that happens when code is loaded that
      generates warnings during error exception processing,
      causing an "invalid re-entry of exception logic",
      interfering with debugging TXR using an uncompiled
      library (.tl files rather than .tlo).
    - Fixed another issue using .tl files: interference
      between library loading and the -C compat option.
      Compatibility is temporarily disabled while
      auto-loading.
    - build macro: code rearranged to eliminate circular
      dependency, preventing modules which depend on the macro
      from loading.
   - Pattern matching: ^#S() and ^H(()) quasiquote patterns
     work now, thanks to a change in the parser.
   - Compiler:
     - Fixed incorrect evaluation order of function arguments
       (when local variables are involved that are subject to
       side effects during evaluation).
     - Fixed issue with compiling defmacro:
       - entire macro form was being retained
       - yet errors not reported against the correct operator
         name: e.g. (defstruct) says that defmacro has
         insufficient arguments.
       - fix also affects tree-bind and other operators.
     - Fixes September 2022 regression in liveness
       calculation, causing certain optimizations to be
       forgone.
     - Fixed incorrect blind register renaming across the
       arguments of a close instruction, which are not
       actually source operands of that instruction.
       - Latent problem exposed when trying to replace V
         register by T register more aggressively.
     - Fixed incorrect live register calculation across catch
       instruction.
       - This has two clobber register operands.
       - Representation of instruction live info was expanded
         to handle two register defs.



                                    TXR 285
                                   2023-03-28


  Features

  - Lib:
    - time (on platforms that have a timezone field in struct tm):
      - functions which convert a destructured time into a
        numeric time, like time-parse-utc, now take the time zone into
        account, and add a displacement.
      - functions which format time now via strftime now set the time
        zone field in the underlying struct tm, so that the %z specifier
        featured in glibc's strftime can be meaningfully used.
    - New function: ignore: synonym of nilf, intended for suppressing
      unbound variable warnings
    - New function: arithp: tests for arithmetic objects, including
      ranges and structures with + method.
    - range/range*: these functions now support non-arithmetic
      types: e.g (range "AAA" "ZZZ" 2) generates ("AAA" "AAC" ...
      "ZZW" "ZZY").

  - TXR Pattern Language:
    - fix exception being thrown in matching a bound variable whose
      value is a lazy list of strings rather than ordinary list.
      - e.g. value captured with @(data ...)

  - Structural Pattern Matching:
    - @nil is now supported in predicates.
      - @(< @nil 42) is like @(< @a 42) but no variable is bound.

  - Syntax:
    - The symbol t can be used in macro parameter lists and tree-bind,
      to specify a pseud-variable which just throws away the
      corresponding value.

  - Compiler:
    - New options mechanism:
      - compile-options struct type
      - *compile-options* special variable.
      - with-compile-options macro
    - New unused variable warnings are on by default.

  Bugs

  - build: fixed regression in building without CONFIG_GEN_GC
    or CONFIG_DEBUG_SUPPORT, which are 1 by default.
  - gc:
    - premature reclamation bug in lisp_parse_impl which is used
      internally and as the implementation for functions that parse
      Lisp, regex and JSON.
    - premature reclamation bug in implementation of FFI enum types:
      neglect to traverse a struct member during gc marking.
    - premature bug in constructor for FFI structs: neglect
      to protect member types from gc in the loop that processes struct
      members.
  - printer:
    - [] object now prints as [] rather than [. nil],
      which isn't incorrect, just ugly.
    - search tree objects now print as #T(...) beyond the maximum
      printing depth, just like #H(...) and others.
  - Vim:
    - Fixed syntax highlighting for decimal integers and
      uninterned symbols.



                                    TXR 284
                                   2022-12-30

  Features

  - OOP:
    - new :inherit clause in defstruct so that inheritance
      bases can be specified by clauses.
      - Motivated by clauses being programmable.
      - Allows defstruct clause macro to bring in bases.
    - new feature: struct preludes.
      - preludes can specify clauses to inject into specific
        defstruct definitions (that have not yet been processed),
        without those definitions mentioning anything.
      - purely a macro-expansion-time feature.

  - Lib:
    - cat-str/join/join-with now allow nested sequences.

  - System Functions:
    - ftw function: the flags argument now defaults to ftw-phys
      if omitted (do not follow symbolic links).

  - compiler:
    - optimizations around catch

  - Awk macro:
    - result of condition in condition-action clause is avaialble
      via a new Awk variable named res.

  Bugs

  - Compilation from command line via --compile now
    sets the self-path variable.
  - Listener: drop security checks on Windows, where they
    don't work and generate false positives.
    - They are geared toward a multi-user system with
      a bona fide POSIX security and file permission model.
  - crypt: remove dubious validator.
    - cannot reproduce the crash issue it was supposed to work around.
  - read-once: now supports global variables properly.
  - crypt: fix ridiculous stack usage, caused by giant context
    structure for glibc's crypt_r.
  - hashing: negative floating-point zero handled.
  - math: expt with a zero exponent yields 1.0. 
    - though works that way already on all platforms, it is now documented and
      assured.
  - compiler:
    - some functions were constant folded that must not be, because
      they are required to allocate fresh objects each time they are called.
    - an instance of runaway recursion in the compiler was fixed in
      constant-folding code.



                                    TXR 283
                                   2022-10-16


  Features

  - Low Level:
    - NaN boxing now works on Android, in spite of its pointer tagging.
    - String objects no longer track their storage allocation size
      on platforms that have malloc_usable_size.
      - The word of storage in a string object thus made available has not yet
        been put to a use.


  - Lisp:
    - New %fun% symbol macro provides name of current function.
    - Separator commas are now allowed in numeric tokens.
    - New functions
      - macroexpand-params:
        - expand parameter list macros made with define-param-expander.
      - macroexpand-place:
        - expand place macros made with define-place-macro
      - macroexpand-match:
        - expand macro patterns made with defmatch.
      - macroexpand-struct-clause:
        - expand defstruct macro clause made with define-struct-clause.
    - Small performance improvements in function dispatch.
      - functions with optional arguments no longer put through slow path
        - this could be listed under Bugs below
      - helper functions for fixed argument dispatch cases now handle
        more cases themselves rather than defer to slow path.
      - use of alloca has been eliminated from the creation of arguments on the
        stack in cases when the size is statically know.

  - OOP:
    - new :postfini clause in defstruct, allowing for finalization
      with order opposite to :fini
    - relaxation of constraint: defstruct can specify multiple :init,
      :fini, :postinit and :postfini clauses.
    - optional arguments :delegate clause now have init expressions
      that are not ignored, but specify the default value.
      - thus delegates can now customize the defaulting of
        optionals rather than being stuck with the target's behavior.
      - when delegates specify an optional parameter that corresponds
        to a non-optional target parameter, they can thus now
        specify a default value, rather than being stuck with nil.

  - Networking:
    - New sockaddr-str function: parse various textual address
      types into appropriate type of sockaddr.
    - New str-addr method in every sockaddr structure,
      for generating textual address.

  - I/O streams:
    - new inc-indent-abs function for incrementing absolute
      indentation, not relatively to current horizontal position.

  - JSON:
    - JSON printing now uses "standard-style" formatting,
      if a the newly introduced *print-json-format* variable
      is set/bound to the value :standard.



  Bugs

  - build: ./reconfigure issue when ./configure is interrupted.
  - str-in6addr bug.
  - hash: don't trim hash seed to 32 bits on 64 bit platforms.
  - JSON: restore stream indentation state if exception occurs
    during JSON printing.



                                    TXR 282
                                   2022-09-16


  Features:

  - New [. expr] syntax. This is also a bugfix because we
    have been printing (dwim . @sym) as [. @sym] without being able
    to read that syntax (read-print consitency issue).

  - NaN boxing representation for Lisp values.
    - enabled by ./configure --nan-boxing
    - 64 bit platforms only.
    - allows floating-point values not to be heap-allocated,

  Bugs:

  - compiler:
    - incorrect scopeing for init expressions of optional parameters.
    - bug in dead-code elimination causing compile-time exception.
    - bug in optimizer affecting code generated by prof operator,
      leading to a wrong result value.
    - compiler now diagnoses if there are too many variables added
      to a lexical frame (more than 1024).
    - numeric ranges in sequence iteration (seq-begin) now work
      with floating-point values.



                                    TXR 281
                                   2022-09-03


  Features:

  - Lib:
    - New search-all library function: like search but finds all matches.
    - New macro: close-lazy-streams: creates a dynamic contour of code which
      closes all streams that were bound to lazy conses during its execution.

  - TXR Pattern Language:
    - The @(next) directive now supports a :noclose modifier.
      - Because @(next) now closes the stream when it's done processing (see
        Bugs below), this new feature is required to opt-out of that behavior.

  - Vim:
    - Improvements to syntax highlighting definitions.

  Bugs

  - ffi: now defends against out-of-range wchar_t values being converted
    to Lisp character type.
  - TXR Pattern Language:
    - When a subquery opens a stream as a data source, that is now closed
      when that subquery is finished processing.



                                    TXR 280
                                   2022-08-09


  Bugs

  - Listener:
    - Fix regression: ~/.txr_history not loading unless ~/.txr_profile exists.

  - Build:
    - Handle failing hard link operation in "make install" so things
      work on Android again.



                                    TXR 279
                                   2022-08-08


  Features

  - Lib
    - missing count function added.
    - regsub
      - now accepts a string in place of the regex,
      - avoids consing a list of pieces to be catenated; works using string-extend.
    - gcd function rewritten for efficiency
      - when arguments fit into a machine word, bignum math is avoided

  - Build/Deployment
    - make install now creates hard links to the txr executable
      called txrlisp and txrvm, useful in scripting with unsuffixed files.
    - txrlisp behaves much like txr --lisp
    - txrvm behaves much like txr --compiled
    - compile-file translates txrlisp to txrvm in hash bang line.

  - Path test functions:
    - All path test functions now use effective UID not real.
    - New function path-components-safe for validating permissions
      along an entire path.
      - Useful for testing whether a path that is supposed to be private
        is actually properly secured.

  - Listener:
    - Security checks on .txr_history and .txr_profile have been revised.
    - Now done with help of path-components-safe in additition to
      path-private-to-me-p.

  Bugs

  - compile-file:
    - tries unsuffixed path before adding .tl, like load.
    - only tries different names on nonexistence error.
    - other exceptios now propagate out of the function.



                                    TXR 278
                                   2022-07-01


  Features

  - New str function for making a string filled with
    repeating pattern.
  - Syntax: stricter check in for/for* loop syntax.
  - I/O:
    - open-fileno (TXR's "fdopen") now takes pid argument, to associate
      the resulting stream with a process.
      - close-stream will subsequently wait on that process, and convert
        the status to a return value or exception.
    - all I/O convenience functions like command-get-linews
      now have a mode-opt argument.
      - For instance "z" can be used for compressed I/O.

  Bugs

  - Build: broken when no HAVE_ZLIB.
  - Command line: broken --free-all option.
  - String output streams: GC issue, occuring in some builds.
  - Listener: properly handle warnings coming out of code that is
    autoloaded during Tab completion.
    - Issue seen when working on TXR, with library .tlo files removed,
      so .tl files are used.
  - Compiler: failure in optimizer.
  - Compression: missing "z" support in open-command.
  - Missing: mode-opt argument of file-get-lines now implemented.



                                    TXR LZ77  :-)
                                   2022-05-31


  Features

  - Zlib integration:
    - New "z" mode option in open-file and open-fileno
      for Deflate compression (reading and writing): reads and writes
      gzip-compatible files.
    - Supported in convenience functions like file-put-string,
      file-get-buf and all those.
    - buf-compress and buf-decompress functions.
    - .tlo.gz files recognized by load as compressed.
    - .tlo.gz files may be catenated just like .tlo files.

  - Lib:
    - tok-str function takes count argument.
    - new spln and tokn functions: like spl and tok, but take
      a count argument limiting pieces returned.

  Bugs

  - tests: load-search test when run as superuser.
  - configure: don't exit when mmap isn't detected.
  - stream-set-prop: return t when :name prop set on file stream.
  - compilation bug in gc.c if HAVE_VALGRIND is on (maintainer mode only).
  - removed workaround for old Cygwin bug in I/O streams.
  - tags.tl renamed to txr-tags.tl to avoid name clash with tags file.
  - cygwin: sh function was wrongly using cmd.exe /c.



                                    TXR 276
                                   2022-05-24


  Features

  - Syntax:
    - printer: now nicely prints (a . @b) rather than (a sys:var b)
      and (a . @(e)) rather than (a sys:expr (e)).

  - Macros:
    - Subtle new expansion rule allows for more thorough expansion
      in situations when a macro and function are defined for the
      same symbol:
      - When a macro expands into the same-named function call,
        and that function call's arguments undergo expansion,
        the result is tried again as the original macro.

  - Command line:
    - New command line option --compile allows compile-update-file
      to be invoked more directly, without having to encode a Lisp
      expression as a command argument.
    - New command line option --in-package allows a package switch
      to take place within the command line. This is used by the
      compilation of stdlib, which takes place in the sys package.
    - In relation to command line: the message during the handling
      of an error exception encouraging the --backtrace option to
      be used is removed. This was a nuisance, and appeared in
      deployed programs that don't offer such an option.

  - Lib:
    - split-str now has a count parameter, to limit how many
      pieces are produced. When the split doesn't use the entire
      string, the remainder appears as a piece. This improvement
      was suggested by Paul. A. Patience in January 2022.
      - The spl function as well as tok-str could use this too;
        that is postponed to another release.
   - New trim-path-seps function for removing trailing path
     separators from a path.

  - FFI:
    - 64 bit bitfields are now supported. this means integer types which
      are 64 bits wide can now be be used as the basis of a bitfield,
      which can therefore be specified as 0 to 64 bits wide.
    - align operator now only increases alignment.
    - New pack operator for packing.
      - (pack (struct s ...)) syntax allows for all members of
        a struct to be packed.
    - The endian types like be-uint32 or le-uint16 can now be used as bit
      fields.
      - The layout takes place like on the machine of that endian;
        e.g. be-uint32 bitfields are filled most-significant-bit
        first.
      - If a bitfield follows a member of opposite endian, it starts a
        new storage cell in a fresh byte.

  Bugs

  - lambda-match: issue with variadic pattern.
  - FFI: bug: all unions were marked as incomplete types.
  - FFI: bug: empty structs/unions had an alignment of 0; should be 1.
  - FFI: bug: null terminated strings didn't work as flexible arrays.
  - copy-path-rec: didn't like trailing slash on source path.
  - FFI: alignment bug: arrays without a dimension were all treated
    as having pointer alignment, 4 or 8 byte, rather than inheriting
    alignment from the element type.
  - FFI: support for bitfields in the face of alignment and packing.
  - FFI: bug in internal type cloning function, leaving the type
    descriptor structure pointing to the original type as its "self",
    manifesting itself as a wrong result from something like
    (alignof foo.bar) when foo.bar has a cloned type (e.g. by
    the align operator).
  - UTF8: Incredibly, a bug was found: the UTF-8 decoder was silently
    eating an incomplete character at the end of the input, instead
    of treating the incomplete sequence as bad bytes, to be mapped
    into the U+DCxx range. Thus there were binary strings which
    were not preserved in the decode -> encode round trip.
  - OOP: Fixed an out-of-bounds stack access in the struct type
    initialization code which deals with suppressing redundant
    initializations of repeated multiple-inheritance bases.
    This more readily affects big-endian systems: showed upon PPC64.



                                    TXR 275
                                   2022-05-10


  Features

  - Architecture support: RISC-V and Loongarch (64 bit).

  - Hashing: new group-map function: group-reduce with
    built-in map pass.

  - Lib: new isecp function: test whether two sequences
    intersect without calculating intersectin.

  - FFI:
    - intmax-t and uintmax-t types.
    - new str-s, bstr-s and wstr-s types for receiving foreign
      string without freeing its memory.
    - after a FFI call, the arguments are processed for
      reverse data flows and memory clean-up in reverse order.
    - with above two features, strtol can be wrapped in FFI,
      including the error-reporting char **end pointer.

  - Loading: new *load-search-dirs* variable.
    - default search directory list includes sysrooted lib dir

  Bugs

  - configure: minor escaping corner cases in in production of
    ./reconfigure script.
  - compiler: package-related bug in file-compilation, reported
    by Paul A. Patience.
  - load: regression: do not try adding suffixes to a path
    which exists; try the given path before anything else
    - Reported by Paul A. Patience.
  - sh, run, open-command and open-process now flush *stdout*
    in situations when it makes sense, standard output is
    ordered between the subprocesses and the parent.
  - listener: Ctrl-Z issue when txr is one of multiple processes
    in a job control process group.



                                    TXR 274
                                   2022-02-24


  Features

  - Configure/Build:
    - 'make clean-c" now cleans the C object files without removing .tlo files.
      - complementary to "make clean-tlo".
    - experimental, not tested support for configuring 64 bit time_t on
      32 bit Glibc.
    - CPPFLAGS (C preprocessor flags) variable noticed and used now.
    - TXR now supports building with -fsanitize=undefined option.
      - you must specify it yourself via platform-flags, etc.
      - configure detects it and puts #define HAVE_UBSAN 1 into config.h

  - FFI:
    - new feature: enumed bitfield type combination now works.

  - Doc:
    - numerous documentation fixes.

  - Lib:
    - cptr-int: allow full unsigned range, so pointers can be specified
      as unsigned integers, or using negative signed values also.
    - New copy-cptr function; copy copies cptr objects.
    - New nandf and norf functions.
    - New function random-sample for one-pass reservoir sampling of a sequence.
    - load: supports catenated .tlo files now
    - cat-files: new function for catenating files, like POSIX cat.
    - find-max uses generic iteration.
    - new find-max-key function.
    - new partition-if function.
    - new list-builder method oust
      - also local function in build macro

  - Getopts:
    - various improvements.
    - opt-help function/method split up into several.

  - Macros:
    - New etypecase macro.
    - New nand and nor macros and functions.
    - opip now allows embedded (ap ...) and so on.

  - Compiler:
    - new optimizations.

  - TXR Pattern Language:
    - new function match-fboundp for testing whether a symbol has a binding
      as a pattern function.

  - Expander:
    - new @,expr hack: quasiquote generates (sys:var ...) or (sys:expr ...)
      based on type of substituted value.
    - macro-time is no longer a special operator, but a macro.

  - Listener:
    - Hack: Ctrl-V Ctrl-J now inserts CR (i.e. new line in multiline mode) rather than a LF.
      - Good for people used to inserting line breaks in GNU Readline.
    - Improvement in method completion.

  - getopts:
    - Numerous improvements, mainly in area of help generation.

  - Autoloading:
    - More nuanced implementation with multiple symbol namespaces, reduces spurious
      loading of modules not actually used.

  Bugs

  - TXR Pattern Language:
    - bug fixed in @(freeform)
    - involves bugfix in lazy-str-get-trailing-list function.
    - filtering now throws when there is an invalid filter,
      due to a fix in the filter-string-tree function.

  - Parser:
    - bug: carriage returns in JSON not tolerated.

  - Configure/Build
    - fixed broken file offset bits detection, resulting in no large
      file support on 32 bit Glibc platforms (regression since 244).
    - fixed broken syntax in unwind.h causing build to break if
      CONFIG_DEBUG_SUPPORT disabled.

  - Macros:
    - sum-each, mul-each: handle no vars case.
    - typecase: return nil from formless clauses.
    - fix broken :key parameters.

  - Lib:
    - carray: allow t and floating 0 in sub and replace.
    - carray-replace: two overrun bugs.
    - separate: wrong return value when seq is nil.
    - time structure: added missing wday and yday slots.

  - Listener:
    - bug handling comments in plain mode.
    - issue handling Ctrl-C in plain mode.

  - Structural Pattern Matching:
    - quasiliteral match wrongly allowing loose prefix matching.
    - `@{nil #/regex/}` wrongly throwing exception.

  - Command Line:
    - -Dvar now binds var to empty string rather than t.
      - this t was some thing inadvertently introduced in 2014.
    - -Dvar=foo=bar (value containing equal sign) works.
    - -Dx,y,z now diagnosed.

  - Vim Syntax Files:
    - improvement in handling multi-line string literals.

  - Search trees:
    - fixed two array underruns found by ubsan.
    - both situations work reliably by fluke in unfixed code due the memory
      cell below the array reliably being zero bits.

  - PRNG:
    - undefined behavior (32 bit shift of 32 bit value) in random function.

  - termios:
    - variables cmspar and crtscts had wrong values on 32 bits due to
      overflow in initialization.

  - General:
    - numerous numeric conversion issues identified by ubsan were
      addressed in various places in the code base.
    - Missing autoload for *in-compilation-unit* caused loading problem for
      compiled code making use of with-compilation-unit.



                                    TXR 273
                                   2021-12-28


  Features

  - compiler:
    - new jump optimizations.
    - register compacting optimization: greatly reduces stack use,
      especially of complex functions, and improves cache locality.

  - pattern language:
    - @{var /regex/} changes:
      - regex no longer ignored when var already has binding
        - text is extracted with regex, then compared to variable
    - @{var (fun ..)} changes:
      - (fun ...) now processed in vertical mode if sole item in line.
      - variable captures lines skipped over in vertical processing.
      - (fun ...) no longer ignored when var already has binding.
        - fun executed like in unbound case.
        - text that would be bound to variable is compared to existing value.

  - structural pattern matching:
    - in quasiliteral patterns, @{var #/regex/} can specify bound variable now:
      - matches text in same way as unbound case
      - matched text must then match content of var

  - lib:
    - new functions: tuples*, rot, nrot, subq, subq, subqual, subst, pairlis.

  - hash tables:
    - use 64 bit hash on 64 bit platforms, rather than 32 bit.

  - search trees:
    - new function tree-count, and length/len works on trees.
    - duplicate keys supported:
      - tree, tree-insert, tree-insert-node have optional argument for
        allowing duplicates.
      - tree-delete-specific-node allows specific node to be
        removed, when removing by key is ambiguous.
    - priority queue support:
      - tree-min, tree-min-node, tree-del-min, tree-del-min-node

  - oop/structs:
    - new feature: application-defined struct clause macros.
    - new: :delegate and :mass-delegate clause macros for
      generating delegate method boilerplate with minimal code.

  Bugs

  - compiler:
    - fix non-working (compile '(lambda ...)).

  - buffers:
    - file-get-buf and command-get-buf use unbuffered I/O
      to read the exact number of bytes into the buffer,
      avoiding reading more bytes than requested.

  - case macros (mainly affecting casequal):
    - fixed 2017 regression causing a key value like ((a b c)),
      which is the single key (a b c), to be wrongly converted
      into a list of three keys.

  - each-match, each-prod, sum-each family of macros:
    - documented and added missing anonymous block

  - maprodo: spurious non-nil return value issue.

  - interpreter: bug in interpreting optional parameters,
    present in original implementation from 2014 (absent in compiler).

  - iteration: gc stability problem in iter-begin and iter-reset.

  - define-accessor: broken argument handling.

  - less/greater: gaping bug, vectors not supported.



                                    TXR 272
                                   2021-11-11


  Features:

  - path manipulation:
    - new path-equal function for comparing paths.
  - pic macro:
    - support for digit-separating commas.
    - support for (...) notation for negative values.
  - FFI:
    - internal improvements and minor optimizations.
    - more ergonomic handling of carray, cptr passed
      by pointer.
  - compiler:
    - now diagnoses constant expressions that throw.
    - improved elimination of wasteful jmp instructions.
    - minor new optimization eliminating a wasteful register copy.
  - PRNG:
    - new random-float-incl function: like random-float
      but the range is [0, 1] rather than [0, 1).
  - syntactic places:
    - new read-once accessor for caching a place so
      that it is read only once even by place mutating
      operators which access it more than once.
    - ifa macro semantics adjusted to take advantage of read-once.

  Bugs:

  - FFI:
    - broken range checks in enum types.
    - bad format calls in enum error handling code.
  - math:
    - bad edge cases in 64 bit conversion (affecting
      32-bit platforms).
  - path manipulation:
    - rel-path bugfixes for native Windows.
  - printer:
    - cases where fallback package syms are wrongly
      printed without package prefix.
  - compiler:
    - ordering issue in load-time.
    - incorrect algebraic transformation of
      (- a b c ...) minus forms.
    - incorrect code generation when compiling catch forms.
    - top-level lambdas no longer captured into D
      registers:
      - not strictly a bug, but undesirable behavior that
        crept in when lambda lifting by load-time was
        introduced.
  - syntax:
    - broken #; syntax for first element of list.
  - listener:
    - bug causing incomplete auto-loading of modules
      during Tab completion.
  - structural pattern matching:
    - unquoted quasiliteral patterns now work.
  - less function:
    - crash when arguments are symbolic and
      the right one is nil.
    - other inconsistent, incorrect behavior for some
      combinations of symbolic arguments.



                                    TXR 271
                                   2021-10-05


  Features:

  - load:
    - new *load-hooks*: defer exeucution to load finish time.
    - used via push-after-load and pop-after-load
  - libtags.txr: script for generating extra tags to jump to
    TXR's C code using Lisp symbols.
  - lib:
    - delcons function: destructively remove indicated cons from list.
    - improvements in string-extend.
    - set-mask and clear-mask macros: shorter code working with masks.
    - new module for quantile estimation: see quantile function.
    - summing and producing variations of each operator:
      - sum-each-prod, mul-each-prod, sum-each-prod*, mul-each-prod*
    - path-search: semantics changes.
    - path access test functions now use read uid/gid rather than
      effective uid/gid.
    - new replace-env function.
    - new *child-env* variable for specifying environment for
      executed process images.
  - FFI:
    - socklen-t type now defined.
    - ffi macro now generates load-time form to avoid repeated
      invocation of FFI type compiler.
    - new cptr-carray function, inverse of carray-cptr.
  - exceptions:
    - system exceptions now store errno in exception message.
    - see string-get-code in doc.
  - sockets:
    - socket options now supported via new sock-opt and set-sock-opt.
    - exception now thrown if socket call fails.
  - compiler:
    - one small optimization improvement and internal improvements.
  - awk:
    - new :fields feature to give fields names and type conversions.

  Bugs:

  - compiler:
    - regression in calculation of output path of compiled files.
    - random perturbation in code generation due to dependency
      on hash table order in an optimization routine.
  - poll: array from alloca passed to free.
  - sockets: bug in sock-peer assignment place.
  - hash: gc problem in copy-hash function.
  - sequence iteration: gc problem.
  - maprodo: problm with single-list argument.



                                    TXR 270
                                   2021-08-30


  Features

  - open-file now supports "x" mode for exclusive create, contributed
    by Paul A. Patience.

  Bugs

  - sequence iteration:
    - garbage collection corruption was discovered via experimentation
      with string ranges (new feature in 269).
      - caused by not properly doing the counter-generation object mutations.
      - Bug is not new: affects bignum ranges, oop sequences.
    - iterating ranges that go from fixnum to bignum now allowed.
  - open-file:
    - "+" mode was behaving like "r" and not "r+" (Paul A. Patience)
    - "w+", "m+" and "a+" refused to create file (Paul A. Patience)



                                    TXR 269
                                   2021-08-28

                          Twelfth Anniversary Edition


  Features

  - networking:
    - getaddrinfo now implements ai-canonname flag.
  - system interface:
    - mmap function now supported, integrated with carray.
      - mprotect, msync, madvise are there.
  - structural pattern matching:
    - new match and match-ecase macros for irrefutable matching.
  - basic Lisp:
    - new ecase family of macros.
  - sequences/iterables:
    - string ranges like "AAA".."ZZZ" are now iterable.
    - iterators (objects from iter-begin) are iterable.
    - sub function allows iterables.
  - FFI:
    - carray-pun function allows displacement
    - improved support for big/little endian types:
      - more efficient when matches local endian
      - aligned reads and writes transfer word at a time.
  - PRNG:
    - new random-buf function for obtaining a block of
      pseudo-random bytes.
  - doc improvements.
  - build/port:
    - builds on FreeBSD; test cases pass.
    - new --no-full-repl option builds trimmed-down listener
      that supports only plain mode editing, not requiring termios.

  Bugs

  - int-str: bug stripping 0x unconditionally regardess of radix argument.
  - format: leading sign state leaking into subsequent conversions.
  - ffi: deffi: broken support for variadic functions.
  - random: bug with modulus that is multiple of 32 bits, found on PPC64.
  - open-file: "+" mode must be equivalent to "r+" not "r".



				    TXR 268
				   2021-08-07


  Features

  - subtypep: arguments can now be struct type objects returned
    by find-struct-type, not only type symbols.
  - JSON:
    - new *read-bad-json* dynamic variable, enabling tolerance for
      trailing commas in JSON arrays and objects.
  - OOP:
    - syntactic infelicity in new* and lnew* operators addressed.
  - streams:
    - close-stream now replays return value if called redudnantly.
    - get-lines/lazy-stream-cons now have optional parameter
      controlling whether the implicit close-stream can throw.
  - listener: plain mode
    - handles multi-line expressions
    - prints prompts if stdin is tty
    - prompts can be turned on with :prompt-on
    - banner is suppressed when stdin isn't tty; more usable in pipes.
  - TXR Pattern Language:
    - @(eof) now takes an optional argument which can bind
      the exit status of the input source. Useful for process pipes.

  Bugs

  - gc: aborts caused by incorrectness in several object-copying functions.
  - correct diagnostic name in remql function.
  - listener: plain mode (txr -n, or input is not a terminal) now
    handles multi-line expressions.
  - build: musl fix for socket.c: need <sys/time.h>.
  - streams: incorrect argument defaulting of second arg of close-stream



                                    TXR 267
                                   2021-07-26


  Features

  - system interface:
    - new getrlimit, setrlimit functions
  - random numbers:
    - buffer objects can be used as random seeds now
  - build:
    - txr.c now recompiled if build_id changes.
    - PDF build is now reproducible even if ghostscript
      and groff don't have patches for this.
  - tags.tl:
    - now supports --emacs argument for Emacs-style tags,
      thanks to Paul A. Patience.
    - other improvements
  - hashes:
    - Hashes now support both and-semantics and or-semantics
      for tables that have both weak keys and values.
      - and-semantics means both key and value must be unreachable
        for the hash entry to disappear.
      - or-semantics means the entry disappears if just the key
        or the value is unreachable.

  Bugs

  - compat:
    - glaring bug fixed going back more than 150 versions.
    - certain effects of the -C compatibility option not
      having their documented effect.
    - caused by referencing the opt_compat variable in global
      initialization functions, at which time opt_compat is
      always zero due to -C not having been processed yet.
  - Test case fixes for missing /bin/sh situation exemplified
    by Guix build environment.
  - op:
    - weirdness in handling nested do (do do do ...) fixed
  - hashes:
    - fixed TXR 235 regression in weak processing, causing
      entries to spuriously disappear from weak hash tables that are only
      referenced by other weak hash tables.
    - fixed incorrect recalculation of hash table counts of weak
      hash tables during garbage collection.
  - carray:
    - missing type checking in a couple of functions, creating
      opportunity for trivial crash.



                                    TXR 266
                                   2021-07-12


  Features

  - built-in macros and special operators are now subject to more
    rigorous syntax checking during the macro-expansion walk.
  - improvements in error reporting
    - built-in macros use compiler-like error reporting now.
    - Lisp files executed from command line rather than loaded, ditto.
    - running make tests out of an editor now takes you to the error line.
  - improvements in doc function, and OpenBSD support.
  - type system overhauled to disallow structs that clash with built-in types.
  - new function called separate contributed by Paul A. Patience.
    - combines keep-if and remove-if semantics
  - new path-manipulation-related functions trim-short-suffix, trim-long-suffix
    and add-suffix.
  - new build-id feature: optional string that can be inserted into TXR
    at build time, displayed by txr --build-id.

  Bugs

  - non-functional chmod.tl test case fixed, thanks to Paul A. Patience.
  - regex: argument defaulting problem in regex-compile.
  - *stderr* stream is now sanely reset during unhandled exception processing.
  - new steps taken to prevent runaway recursion in exception processing.
  - streams:
    - close-stream function refuses to close stderr.
      (previously refused only stdin and stdout.)
    - put-char, put-line: lack of type checking on stream argument.
  - bug in with-resources problem fixed, reported by Paul A. Patience.
  - doc ignores BROWSER variable if it is empty.



                                    TXR 265
                                   2021-07-04


  Features

  - requirements change in new long-suffix and short-suffix functions:
    - dot is now part of suffix.
    - leading dot is not a suffix delimiter: e.g. .bashrc is not a suffix.
    - trailing path separators ignored, like in base-name.
  - regex: optimization function exposed.
  - constantp function now recognizes more kinds of expressions:
    - (+ 1 (* 3 4)) is constantp, as is (symacrolet ((a (+ 2 2))) (* b 3)).
  - doc function
    - now handles situations in which xdg-open blocks until browser exits.
    - now reacts to BROWSER variable, and if xdg-open is not found,
      falls back on the first of a long list of possible browsers.
  - filesystem interface:
    - path-cat function is now variadic: (path-cat "a" "b" "c" ...).
    - new path-search function, searches for an executable by name in path,
      defaulting to the system's PATH.
  - sequences:
    - new find-true function; like find-if, but returns the true value
      that the predicate produces, rather than the item from the sequence.
  - I/O streams:
    - argument defaulting tightened; functions no longer treat a nil
      value for the stream argument as a missing argument.
  - stack limit:
    - minimum limit now imposed when the system's stack limit is too low,
      rather than disabling the mechanism.
    - stack limit is now always on, even if we don't obtain a value
      from the system or that value indicates that there is no limit.
  - documentation infrastructure:
    - improvements from Paul A. Patience integrated.
    - doc workflow catches more kinds of problems.
  - listener: empty EDITOR variable now treated as missing.

  Bugs

  - build: regression in separate-directory build.
  - parser: regression: not working with byacc.
  - compiler: a number of bugs in inline lambda implementation.
  - op: subtle bug in do operator; code refactored.
  - base-name function: problem with empty suffix.
  - listener: end-of-line/buffer visual glitch in selection.
  - trie: bugs in regex-from-trie function, now covered by tests.
  - regex: print/read consistency problem printing n-ary operators.
  - doc: *doc-url* variable not special, as documented.
  - getopts: throwing sys:opt-error instead of usr:opt-error.
  - command line: lack of robustness in -b option fixed.
  - documentation: numerous fixes.
  - packages: find-symbol was behaving identically to find-symbol-fb.
  - signals: itimer-prof variable misspelled as itimer-prov.
  - search trees: documented tnodep function now actually exists.
  - stack limit: fix crash when system stack limit is RLIM_INFINITY.



                                    TXR 264
                                   2021-06-25


  Features

  - system interface:
    - TXR no longer relies on popen for open-command.
    - glob function accepts multiple pattern arguments and
      uses multiple calls to the C function with GLOB_APPEND.
  - parser:
    - parsing Lisp or JSON from a string now produces error
      if there is any trailing material in the string.
  - paths:
    - new functions short-suffix and long-suffix for robustly
      extracting the suffixes/extensions of path names.
  - lib:
    - new functions cxr and cyr for traversing cons-cell
      structures using a car/cdr path binary-coded in an integer.
    - mismatch/rmismatch better optimized for strings
      - starts-with and ends-with use these.
  - structural pattern matching:
    - new looping macros while-match, while-match-case, while-true-match-case.
  - parser:
    - no longer wastefully allocates dynamic string when scanning a
      floating-point token.
  - tests:
    - target-installable test cases are now relocatable (can be installed
      at any path) due to a small improvement in the run.sh script.

  - program-wide:
    - share/txr/stdlib moved to stdlib.
    - type mismatches when a string is expected now give
      function name in error diagnostic.
    - stack overflow protection is introduced:
      - in key places, TXR detects whether the stack pointer is over a
        predetermined limit and throws a stack-overflow exception.
      - controlled by set-stack-limit function.

  Bugs

  - fixed wrong result from (rmismatch #() ()) and (rmismatch "" ()).




                                    TXR 263
                                   2021-06-17


  Features

  - New macro named flow, providing the syntactic sugar for
    using an opip function on a value.
  - I/O:
    - the *stdnull* stream lazily attaches to /dev/null if
      fileno is invoked on it
  - formatted printing:
    - format: new precision modifier - for zero instead of plus sign.
    - pic macro: takes advantage of format work to generate better code.
  - subprocesses:
    - some file descriptor saving-restoring manipulations moved
      into child process (in open-process, open-subprocess, run)
    - diagnostic for situation when *stdout*, *stdin* or *stderr*
      are redirected to something that cannot produce a file descriptor.
  - match-fun/txr-if
    - documented that input can be a stream
    - documented that input can be a single string
  - txr-case:
    - if input is a stream, it is now converted to a lazy list of lines,
      so that the txr-case construct effectively backtracks over the
      data as it tries successive cases.
  - command-line
    - new --noprofile option to invoke listener without processing
      ~/.txr_profile file.

  Bugs

  - format: numeric handling maintenance
    - poor behaviors identified and revised.
    - requirements clarified.
    - cemented in test cases.
  - exceptions:
    - unwind dynamic environment when tracing unhandled exception
      - solves problem when exception goes off while *stderr* is redirected.
  - subprocesses:
    - diagnostic for situation when *stdout*, *stdin* or *stderr*
      are redirected to something that cannot produce a file descriptor.
  - macros:
    - fixed TXR 191 regression in defsymacro: expanding the replacement form
      before associating it with the symbol, rather than taking as-is.
  - quasiliterals:
    - fixed issue arising when a macro invoked as a @(...) expression in a
      quasiliteral expands to a non-string atom.
  - math:
    - forbid dubious inequality comparisons like (< 1 "abc") which
      became unintentionally allowed due to numbers being iterable.



                                    TXR 262
                                   2021-06-11


  Features

  - structural pattern matching:
    - new feature: quasiquote matching.
  - JSON:
    - improved escaping of JSON output for safe embedding in <script> tags.
    - new JSON pattern matching.
  - text processing:
    - new pic macro for formatting using pattern similar to perl's
      format or PRINT USING in BASIC languages: ####.# <<<<<<.
      - works by compiling to fmt calls.
  - FFI:
    - bad FFI call diagnostics now have function name.
    - failures in dlsym function converted to better diagnosis.
    - carray objects can be passed to cptr argument now.
    - new deffi-struct and deffi-union macros for less verbose
      definitions without a typedef.
  - lib:
    - new fill-vec function for efficiently filling an area of a vector
      with repetitions of a value.
    - reduce-left rewritten with generic sequence iteration, for
      better efficiency (e.g. not consing memory over vectors).
    - sum and prod functions likewise.
  - expander:
    - fixed issue in defun expansion interfering with defining a macro
      and then a function of the same name which calls the macro.
  - parser:
    - new *read-unknown-structs* Boolean variable
      - if set, the reader can read #S syntax which names undefined
        structure types, without blowing up.
      - used in tags.tl, which can therefore handle source code
        that contains struct literals.
  - compile/eval:
    - improved coordination between error exceptions, compiler
      error messages sent to the error stream, and deferred warnings.

  Bugs

  - listener:
    - doc function not working in Cygwin/Cygnal port.
    - macro and operator completion after ' (quote) character;
      so that (doc 'wh[Tab] will complete on a macro name like while.
  - system interface:
    - mkstemp build problem problem affecting Solaris and other platforms.
  - printer:
    - added missing handling for printing (sys:struct-lit ...) syntax
      as #S syntax.
  - parser
    - bug with #; commenting syntax not playing nicely with #S literals.
  - JSON:
    - test cases on Cygwin work.
    - JSON print-read consistency problem addressed.
  - FFI:
    - memory leaks in FFI type system when struct type is redefined.
    - bug in deffi causing the libffi ffi_prep_cif_var function to
      always be used, even for non-variadic functions.
    - FFI now properly calculates the structure member descriptor arrays
      for libffi, and fakes them out for arrays and unions also.
      This should address problems with passing small structures by value.
      - The material is calculated lazily: not done for types that are
        never used as by-value parameters or return values.
  - format:
    - fix bugs in leading zero in precision field of format specifier.




                                    TXR 261
                                   2021-06-01


  Features

  - JSON support:
    - #J syntax in TXR Lisp
    - allows quasi-quoting and circular notation.
    - I/O with JSON objects, with convenience routines like
      file-put-json, and others.
    - Vim syntax highlighting support for everything.
  - parser:
    - new parse-errors function for retrieving number or
      parse errors from stream or nil if no errors.
  - filesystem:
    - new functions tmpfile, mkdtemp and mkstemp.
  - lib:
    - chr-iscntrl now recognizes Unicode C1 control character block,
      not only the C0 from ASCII.

  Bugs

  - compiler:
    - invalid move into register T0 generated when compiling catch code,
      causing assembler to throw error.
  - search trees:
    - GC abort caused by tree-delete/tree-delete-node.
  - parser:
    - GC bug due to storing lookahead token in parser using
      a wrong-way assignment.



                                    TXR 260
                                   2021-05-26


  Features

  - structural pattern matching:
    - values in hash pattern can be now omitted with usefully nuanced
      semantics.
  - parser:
    - unterminated expression diagnostic now given in in format that lets
      editors jump to the start of the unterminated construct.
  - compiler:
    - better translation strategy for global var definitions.
  - documentation improvements.

  Bugs

  - lib:
    - buggy :wrap and :reflect in window-map fixed.
    - case{q*,ql*,qual*} macros failing to expand key expressions.
  - compiler:
    - fix compile-file warnings being deferred to end of surrounding load
  - ffi:
    - crash when carray object passed as argument to foreign function.
  - arithmetic:
    - several bugs in the area of bignum to 64 bit conversions.
  - listener:
    - don't complete on symbols that are just interned, with no binding.
  - doc function now handling symbols like <= that use HTML codes in
    the document.



                                    TXR 259
                                   2021-05-13


  Features

  - lib:
    - New rel-path function for calculating relative path
      between two directories.
    - format function's ~x/~X supports printing buffer
      objects in hex.
  - structural pattern matching:
    - new each-match family of macros for iterating over
      sequences, with destructuring.
  - search trees:
    - numerous new functions
    - tree iterators support sub-ranges of trees
    - trees are now sequences and can be mapped over with
      mapcar, each and other functions.
  - build:
    - fixed issue with ./reconfigure overwriting itself,
      causing instability.
    - ./reconfigure takes configure parameters to be added.

  Bugs

  - join-with segfault on character (not string) separator.
  - parser:
    - regression introduced in 258: crash when the #; syntax
      for commenting out an object is processed.
    - bug in handling certain objects, such as string
      literals, as top-level forms in a file.
  - compiler:
    - failing to diagnose wrong number of arguments in calls to lexical
      functions that have been lambda-lifted to the top level.
  - buffers:
    - int-buf and uint-buf functions wrongly referring to
      buffer's allocated size instead of its length.
  - sha256/md5:
    - memory leak in use of buffers.



                                    TXR 258
                                   2021-04-30


  Features

  - Structural pattern matching now supports quasiliteral patterns
    for matching into strings.
  - Search tree module supports a way to start scanning nodes
    in order at or above a given lower bound key.
  - improvements in Vim syntax highlighting files.

  Bugs

  - GC issue in sequence iterators: not marking iterated object
    when it's a structure.
  - GC issue in parser.
  - lexical-var-p: no longer wrongly returns t for locally bound
    special variables.
  - regression in mapcar*, going back to 240.
  - search tree module:
    - massive gc problems
    - broken tree-lookup



                                    TXR 257
                                   2021-04-22


  Features

  - parser:
    - Invalid UTF-8 bytes and characters now allowed in literals and regexes.
    - Treated using rules consistent with behavior of text streams.
  - doc:
    - General improvements in documentation, many thanks to Paul A. Patience.
  - build:
    - Test suite no longer requires .expected files which are empty;
      they materialize on-the-fly and make cleans them away afterward.
  - streams:
    - stream-max-len behavior changes for strings. Some small bugs
      fixed in this area.
  - structural pattern matching
    - new @(scan) operator for finding a match over a list
    - new defmatch macro for defining new pattern operators
    - new pattern operators @(end) and @(sme) defined using defmatch
  - TXR:
    - Debug output for @(gather) directive reports exact list of variables
      that were not bound.
  - compile/eval:
    - compile-error macro now prints error on *stdout* in addition to
      throwing exception.
      - upshot of this is that this helps editors navigate to the error.
      - previously this worked for warnings, not errors.
    - new binding operator: mac-env-param-bind
  - port status:
    - TXR ported to OpenBSD, amd64.
  - internal:
    - New C function dis that can be used debugging TXR with gdb to
      disassemble VM code.

  Bugs

  - compiler:
    - (call (fun f) ...) forms not registering the reference to f,
      causing lambdas to be incorrectly lifted to a scope where they
      lose access to a needed lexical function.
    - incorrect handling of trailing arguments in immediately-called lambda.
    - bad diagnostic in compile-file when output file can't be opened.
    - constant-folded (call ...) expressions not quoted.
    - bug in dead code elimination (optimization level 6) causing
      references to nonexistent assembly language labels.
    - bug in frame elimination (optimization level 2) not initializing
      some registers in code that can execute more than once due to loops.
  - GC:
    - Bug in sys:gc function fixed, whereby it wrongly resets the
      internal flag which requests a full collection, leading to corruption
      (since that flag is sometimes set for reasons of correctness).
  - regex:
    - The regsub function was found to have destructive behavior,
      contrary to documentation.
  - lib:
    - fixed a bug causing the functions base-name, dir-name and TXR's
      sysrooting calculations to be wrong on platforms where sizeof(wchar_t)
      is 2 (Windows/Cygwin) and on MacOS.
    - fixed the bogus assumption in the code, introduced in 2015, that there
      are platforms with four-byte wchar_t which don't align L"..." literals
      to four byte boundaries, and that MacOS is one of them.
  - continuations:
    - fix stack alignment on amd64 under clang.
      - discovered during OpenBSD port, but not an OpenBSD problem.
  - build:
    - make referenced in a few places instead of $make, causing
      some nuisance error messages on platform where GNU Make is gmake.



                                    TXR 256
                                   2021-04-07


  Features

  - Compiler:
    - Compiler now checks number of arguments in a function call
      against its definition.

  - Doc:
    - numerous improvements in the manual, especially HTML output.
    - New library function doc for documentation lookup:
      - (doc) -> open manual with default browser
      - (doc 'cons) -> open manual to specific symbol
    - INSTALL document maintained.

  - Awk:
    - :name argument not restricted to symbol, but any valid
      object usable as a block name.

  Bugs

  - Compiler:
    - fixed incorrect constant folding of call function.
    - some instances of misleading diagnostic wording fixed.
    - fixed regression in source location info propagation
      - causing errors not to have location information in some cases
      - caused by recent optimization work.
  - OOP:
    - fixed lack of hygiene in qref operator with regard to
      a.?b syntax, causing mutiple evaluations of a.
  - GC:
    - fixed bug in weak hash processing dating back to the
      initial weak hash implementation in 2009.
  - Awk:
    - The value of the rs (record separator) variable being
      wrongly compiled as regex syntax even if it is a string object
      that must be a fixed pattern.
  - Lib:
    - bug in UTF-8 decoding function
      - affecting situations when buffered bytes are decoded as utf-8
        (I/O streams not effected).
      - incorrect behavior when invalid bytes are present;
        valid UTF-8 not affected.
    - func-optparam-count: function was returning bogus value
      for interpreted functions.



                                    TXR 255
                                   2021-03-26


  Features

  - TXR has been ported to Arm64 Mac OS Darwin (Apple M1).

  - lib:
    - argument to cat-str treated via sequence iteration
      for better efficiency on non-lists.
    - likewise for the poll-list argument in poll.
  - compiler:
    - optimization improvements
      - The VM's T registers can now be used for function arguments,
        promoting further optimizations, and eliminating the
        need to allocate a variable frame for arguments.
      - several other optimization improvements.
      - code improvements in compiler.
  - FFI:
    - float type used as variadic argument in deffi and deffi-cb
      now promoted to double, preventing a programmer pitfall.
  - VM:
    - execution of VM code is now interruptible by signals,
      most notably the SIGINT generated by Ctrl-C.
      - this is done in a way that shows vanishingly low overhead.

  Bugs

  - ffi: fixed missing support for retrieving ushort type from
    misaligned buffer
  - tests:
    - on Mac OS, the socket-basic.tl test passes on the stock OS
      configuration, not requiring limit on UDP datagram size to
      be relaxed via sysctl.
    - make -j retest now works reliably via a recursive invocation.



                                    TXR 254
                                   2021-03-10


  Features:

  - compiler:
    - elimination of function calls that produce unused values.
      - this compiles down to just "nil":
          (let ((x (cons y z))) (set x (cons u v)) (set x nil) x)))
    - elimination of unused accesses to globals
    - elimination of unused lambdas.
    - optimization control: new variable *opt-level*, valued 0-6.

  - lib:
    - new functions join and join-with to complement the tired old
      cat-str for joining strings and characters.
      - (join-with ":" "a" "b" "c") -> "a:b:c"
      - (join "a" "b" "c") -> "abc"

  Bugs:

  - broken sort function over vectors and strings
    - failing to return the sorted object



                                    TXR 253
                                   2021-03-06


  Features:

  - build:
    - parallel builds allowed with ./configure --parallelmake
    - after above, make -j is supported.
    - recommended for development, not distro builds.

  - compiler:
    - new optimizations
      - order of optimization passes rearranged
      - new peephole patterns.
      - Pattern-matching Ackermann 48 times faster
        than interpreted
      - functional combinator expressions are now automatically
        hoisted to load time.
        - E.g. [chain .foo car list] is now computed once when
          the code is loaded, and then referenced.

  Bugs:

  - compiler:
    - mistake in (if (equal ...) ...) pattern corrected,
      allowing corresponding reduction to take place.
    - fixed bug in frame depth calculation when load-time forms
      are involved.
    - fixed bug causing redundant dead code to be added to load-time.

  - hashing:
    - fixed bug causing hash-equal to produce zero for floats
      and bignums
      - equal-based hash tables using bignums or floats as keys
        are affected.




                                    TXR 252
                                   2021-02-28


  Features:

  - compiler:
    - new optimizations introduced:
      - elimination of frames for non-captured lexical variables
      - elimination of blocks in self-recursive functions
      - more compact frame size for closures
      - strength reduction of equal (helps pattern matching)
      - list construction optimization:
        - e.g. (cons 1 (cons 2 3)) -> (list* 1 2 3) and more
      - other algebraic reductions.
      - aggressive constant-folding of over 300 library functions.
      - new control-flow and data-flow analysis:
        - removal of dead registers
        - elimination of inefficiently used temporary registers
        - comprehensive dead code removal

  - structural pattern matching
    - internal code cleanup, improvements and improved
      diagnostics for hash patterns.

  - syntax:
    - obj.[fun ...] syntax changes meaning; it is now
      method dispatch.
      - obj.[method ...] is to [fun ...] as
        obj.(method ...) is to (fun ....)
    - improved diagnosis of invalid dotted forms.

  - library:
    - list-builder methods now return the object, allowing
      chaining like (new list-builder).(add 3).(get)

  - vm:
    - backwards compatibility jump: TXR 251 generates version 6
      object files (.tlo) and will not read older ones.
    - Some obsolescent instructions have been removed from the
      instruction set.

  - TXR Pattern Language:
    - function calls, including indirect calls via @(call ...)
      are now considered non-matching directives, thus not
      calling for the input source to be opened.

  Bugs:

  - math:
    - fixed out-of-bounds memory access in or and xor
      functions when the arguments are bignums.
  - build:
    - bug fixed: not dealing with spaces in configuration arguments when
      generating ./reconfigure script
  - printer:
    - obscure bug in printing lambda expressions fixed,
      triggering function lookup and expansion at print time.
  - compiler:
    - fixed internal error in compiler when compiling
      certain cases sys:switch forms generated in certain cases
      of caseq/caseql.
    - assignment to a function binding being internally marked as
      an a free variable reference by the compiler, rather than
      a free function reference.
    - incorrect compilation unwind-protect form when the
      protected form is trivial, like a literal constant.
  - TXR Pattern Language:
    - fixed broken implementation of @(call ...), in several independent
      aspects.



                                    TXR 251
                                   2021-02-08


  Features

  - structural pattern matching:
    - now allows back-referencing with existing variables
      outside of the pattern, greatly improving expressiveness.
    - new @(with) operator, allows match between side pattern
      and side object in parallel with main pattern and main object.
    - @(let) renamed to @(as).
    - clauses of @(and) now in same scope allowing back-referencing.
    - redesign of lambda-match, using special argument matching rather
      than a list pattern against the argument list.
      - functions based on pattern matching now perform much better
    - new :match parameter macro:
      - adds pattern matching to any function in any situation
      - supports mixture of regular arguments and pattern matching.
    - predicate pattern syntax and semantics redesigned.
      - predicates now have multiple arguments
      - variable can be inserted anywhere in a predicate call,
        including dot position
      - variable can be omitted, giving rise to the object being
        passed as the rightmost argument to the predicate call
    - @(op ...) pattern is removed:
      - not necessary due to improved predicate handling.

  - compiler:
    - new optimizations
    - error location reporting improved.

  Bugs

  - structural pattern matching
    - fixed bad hygiene in match-case due to not using gensym.
  - lib:
    - fixed crash in nullify and iterable, when argument is
      a C object that is not a struct.
    - fixed long-standing bug in multi-sort: when the list(s)
      are empty, it must return a list of empty lists, not nil.
      E.g. [multi-sort '(nil nil nil) less] now returns
      (nil nil nil) as documented, and not nil.



                                    TXR 250
                                   2021-01-31


  Features

  - structural pattern matching:
    - new @[...] predicate operator.
      - can capture object, as well as value of predicae
    - better code generation

  - compiler:
    - jump threading optimization
    - dead code removal
    - peephole optimizations


  Bugs

  - structural pattern matching:
    - numerous new test cases introduced showing various
      breakage, and fixed.
    - code substantially refactored
    - @(or ...) pattern handled in new way.
  - compiler:
    - fixed totally broken treatment of append-each operator
      - destructively catenating lists
      - not observing append semantics w.r.t. generic sequences.
  - sub-str: now subject to compatibility; -C 215 or lower
    restores the behavior of always copying the input string,
    even when sub-str covers the entire string.
  - lazy strings: instance of invalid substrucure sharing
    fixed in lazy-sub-str, causing incorrect behavior,
    showing up as strangeness in @(freeform) processing
    and anything else relying on lazy-sub-str.
  - fixed broken @(rebind) directive.
    - not removing variables from environment if left hand
      side is a pattern with multiple variables.
    - wrongly removing right hand side variable from environment.



                                    TXR 249
                                   2021-01-24


  Features:

  - structural pattern matching:
    - variables can now back-reference so that (@a @a)
      matches a two-element list whose items are equal.
    - @(some) and @(all) operators work with any sequences, not just lists.
    - New pattern-matching @(coll ...) operator for collecting
      from a sequence those objects which match.
    - New @(hash ...) operator for matching hash tables on keys,
      values or both.
    - Matching ranges using range objects is now supported,
      e.g. #R(@a @b) matches a range, and binds a and b to its from and to.
    - Trivial patterns (those containing no operators or variables) are
      now handled more efficiently. E.g. the pattern (1 2 3) or #(1 2 3)
      will just be tested using equal as an atom, rather than
      compiled into individual tests over the elements.

  - hashing:
    - hash-revget now uses equal equality for finding matching
      values in the hash table, rather than eql.


  Bugs:

  - structural pattern matching:
    - fixed order of evaluation problem in @(require)
  - iter-step: no longer traverses into terminators of improper lists, which
    caused situations like (each ((x '(1 2 . 3))) ...) to iterate indefinitely.
  - fixed a regression which caused carrayp, hashp, random-state-p, regexp and
    struct-type-p to indicate true as 1 instead of t.
    - internally, the way t is initialized when TXR starts up has also been
      improved as a result.
  - parser:
    - fixed badly designed low-precedence of the @ token: the one applied to
      expressions as in @(foo).
  - printer:
    - fixed the print/read ambiguity that both (rcons @a @b) and @(rcons a b)
      printed as @a..@b.
    - @(rcons ...) now prints as @(rcons ...) and never as the x..y notation,
      so only (rcons @a @b) prints as @a..@b.
    - we also know that only (rcons @(a) @(b)) prints as @(a)..@(b), and
      thanks to the parser fix mentioned above, @(a)..@(b) parses as
      (rcons @(a) @(b)).
  - places:
    - The function name call-delete-expander was wrongly in sys package, rather
      than the usr package, as documented.
    - Addressed runaway recursion in place expansion logic, causing, for
      instance the expansion of (let (a) (set a #1=(#1#))) to recurse
      infinitely.
  - manual: fixed wrong 2020 date.



                                    TXR 248
                                   2021-01-20


  Features:

  - hashing:
    - new hash-key-of function: get all keys that map to the specified value.

  Bugs:

  - compiler regression: incorrect reduction of (and <true-constant>) forms
    to t instead of <true-constant>.



                                    TXR 247
                                   2021-01-19


  Features

  - lib:
    - structural pattern matching introduced.
    - prog2 macro introduced.
    - progn, prog1 and prog2 are now also functions.

  - build:
    - configure's test for how to define inline functions fixed.
      - hopefully this will fix things for Brew.
    - linker options and library flags are now separate;
      there is a new platform-ldlibs configure option.
    - LDLIBS variable is now honored, not just LDLIBS.

  - gc:
    - finalizers now registered during finalization processing
      may be called in the same phase, if they are eligible.

   Bugs

   - show-stopper regression in mapcar/maprod.




                                    TXR 246
                                   2020-12-31


  Features:

  - Library:
    - shuffle and nshuffle functions take optional random state
      argument now.

  Bugs:

  - gc:
    - bug in finalization leading to assertion in garbage collector.
      - affects situations in which finalizers are explcitly called,
        rather than naturally occurring during garbage collection.
    - flaw in object finalization logic causing unnecessary full
      generation to be requested.
  - awk:
    - fixed regression in fconv macro (probably dating back several years):
      - the conversion shortcuts like i, x, o, r became unavailable
        due to being sys: symbols rather than usr: symbols.



                                    TXR 245
                                   2020-12-24


  Features:

  - Android is now a supported target platform: builds in termux environment.
     - TXR executable builds as PIE, which is mandatory on Android.
     - test suite passes nevertheless: PIE-related has not been observed.

  - System Interface:
    - env-hash now returns the same hash object every time it is called,
      whose contents are updated by setenv, unsetenv and getenv.

  - Build:
    - C compiler now operated in C99 dialect, except in maintainer mode.


  Bugs:

  - math: bad edge-case in int-flo function affecting 64 bit systems.
  - time: do not offer a make-time-utc function if we have neither timegm nor
    setenv in the C library; we don't simulate setenv with putenv any more.
  - printer: don't print leading zeros in characters printed in hexadecimal.



                                    TXR 244
                                   2020-10-10


  Features:

  - Build:
    - Dropped dependency on Bison/Byacc and Flex:
      - TXR now ships the generated parser and scanner source.
      - The --maintainer option must be given to configure to enable
        regenerating these sources, otherwise the shipped ones are used.

  - Lib:
    - New trim-left and trim-right functions for removing a suffix.
    - Time-related functionality moved out of lib.c into a new time.c module.
    - New time-nsec function for nanosecond-precision time.
    - PRNG uses nanoseconds now in seeding, rather than microseconds.

  - Listener:
    - New quip function produces a randomly selected humorous line,
      suitable for printing out of the ~/.txr_profile startup file.

  - Compiler/VM:
    - movi family of instructions (move immediate operand into register)
      are deprecated and no longer used by the compiler.
      - It is cheaper to the integer or character operand in a D register
        already, since no instruction needs to be executed to get it into a
        register.
      - The downside is that code which uses a large number of small integer
        literals can now run out of D registers, whereas previously
        it woudl have not run into any limit.

  Bugs:

    - output-side @(repeat) was still not finding Lisp variables embedded
      in braced expansions.
    - fixed two defects in the implementation of the WELL512a pseudo-random-number
      generator.
      - compat option (-C 243 or lower) restores broken PRNG behavior for
        reproducibility of old PRNG sequences.
    - regression in two-or-more-sequence form of mapcar: it was not
      converting the output to the type of the leftmost sequence.



                                    TXR 243
                                   2020-09-01


  Features:

  - TXR:
    - output-side @(repeat) directive more intelligent:
      - now identifies variables referenced in Lisp code
      - many uses of :vars now unnecessary
      - variables identified in expansion pass now, before query execution

  - OOP:
    - diamond problem in multiple inheritance addressed.
      - duplicate inheritance bases no longer cause multiple
        calls to :init, :postinit and :fini handlers.

  - Lib:
    - new reject funtion, complements select.

  Bugs:

  - FFI:
    - several bugs addressed in the allocation of bitfields.
    - documentation of Bitfield Allocation Rules also updated.



                                    TXR 242
                                   2020-08-14


  Bugs

  - TXR: fix serious regression introduced in TXR 235, affecting
    correctness of behavior in multiple places.
  - listener: fix regression introduced in TXR 239, causing funny
    behavior when invoking Tab completion on keywords and qualified symbols.



                                    TXR 241
                                   2020-08-08

                          Eleventh Anniversary Edition


  Features

  - MIPS (32 and 64 bit) is a a target platform now.
  - Lib:
    - New list-seq, ved-seq and str-seq functions.
    - New maprodo function: like maprod, but returns nil.
    - New each-prod, collect-each-prod and append-each-prod operators:
      - traverse cross product of the sequences rather than in parallel.
    - crc32 has initial crc argument, allowing multi-step
      crc32 calculation over multiple objects.
    - New iterable predicate function for detecting whether object is iterable.
  - Structs:
    - New iteration protocol
      - comes in two flavors, using either two or three methods.
  - System Interface:
    - New strerror and strsignal functions.
    - Argument of exit now optional, defaulting to success.
    - New opendir, readdir and closedir functions for lower-level directory
      traversal (complementing ftw and glob).
    - stat family of funtions can now fill an existing struct.
  - TXR:
    - @(if)/@(elif)/@(else)/@(end) syntax now supported in @(output).
      - @(if test then [else]) Lisp form still supported.
  - Listener:
    - new *-1, *-2, ..., *-20 macros for referencing prior values
      relatively.
  - Symbols:
    - packages can now be created weak. If a symbol is reachable only through a
      weak package, it can be garbage-collected.
  - FFI:
    - new cptr-get and cptr-out functions for accessing through a cptr.
  - Networking:
    - New address parsing functions inaddr-str and in6addr-str.
      - support for port number and / prefix notation.

  Bugs

  - listener: bogus permission complaint when .txr_history file missing.
  - structs:
    - static slot handling in autoload leading to spurious errors.
    - autoload on instance slots also to prevent spurious no such slot errors.
  - parser:
    - minor omission in syntax error diagnostic logic leading to internal token
      values being printed as if they were characters.
  - TXR: regression in vertical-horizontal fallback (see 7006ede9).
  - printer: bugs in printing uref and qref syntax.
  - parser:
    - fixed breakage on some platforms like newer Mac OS X due to Flex
      scanner containing an #include <unistd.h> in the middle of lex.yy.c,
      after we have included our headers which define numerous macros.
    - eliminated calls to isatty from the lexer.
  - cygwin:
    - broken cat-str and split-str family of functions when using a character
      object as a separator.



                                    TXR 240
                                   2020-06-06


  Features

  - New iteration paradigm for sequences.
    - iter-begin function takes an iterable, returns an iterator.
    - iter-more tests whether iterator has more items.
    - iter-item gets first available item
    - iter-step takes an iterator, returns either new iterator,
      or the same iterator, mutated.
    - integrated into sequence processing functions.
    - works for sequences, as well as integers and ranges.
    - e.g. [mapcar list '(a b c) 1] -> ((a 1) (b 2) (c 3))
  - each, collect-each, ... operators work with this paradigm.
  - mapcar, mappend, mapdo, maprod, maprend now optimized:
    - work well with sequences of all types
    - allocate parallel iterators on the native stack

  Bugs

  - maprod bug: wrongly reducing to mapcar, rather than mappend
    in the one-sequence case.
  - fixed interpreter segfault on (each ()) expression.



                                    TXR 239
                                   2020-06-02


  Features

  - Minor optimizations in library:
    - many instances of internal (format nil ...) calls replaced with cheaper
      string catenation operations.
    - consing reduced in the compiled implementation of string quasiliterals.
    - search, rsearch and update functions switched to seq_info.

  Bugs

  - compiler: showstopper bug fixed: operators in the each family, and the
    dohash operator were missing the implicit anonymous block.
  - vm: fixed interal bug: when diagnosing the situation that an anonymous
    block is not visible, format was called with excess arguments, hijacking
    the situation with a different exception.
  - lib: fixed broken rsearch function, and a minor flaw in the diagnostic
    generated by search and rsearch for a wrongly typed key object.
  - signals: fixed mismanagement of the sigaltstack memory.
  - streams: improved dubious integer format string detector logic that is
    invoked at global initialization time.



                                    TXR 238
                                   2020-05-18


  Features

  - Compiler:
    - optimization of load-time and fine-tuning of its semantics.
    - compiler now does lambda lifting: lambdas that don't reference
      lexical variables are created one time at load-time.
      - Now almost no penalty for moving a defun into a labels/flet,
        unless capture is introduced.
  - Lib:
    - Functions countqual, countql, countq, count-if, some, all, none
      now use the sequence iteration, so they are more efficient on
      non-list objects.
      - This is part of a slow-moving, on-going effort.
    - sort and shuffle are now non-destructive
      - the original destructive functions are available as
        nsort and nshuffle, respectively.
      - compat mode (value 237 or lower) restores destructive behavior.
    - New assert macro: something that has been conspicuously missing.
  - System Interface:
    - isatty function exposed.

  Bugs

  - sockets: bug in formatting IPv6 textual address.
  - symbol-function: fix failure to expand lambda expression arguments.
  - compile function no longer wastefully expands already expanded input.
  - configure: ./configure --help no longer clobbers ./reconfigure script.



                                    TXR 237
                                   2020-04-26


  Features

  - I/O:
    - get-line-as-buf function: read a line from a text stream
      as a buf object: saves storage compared to a string.
    - poll function now enables async signal handlers invocation,
      allowing it to beinterrupted.

  - Parser:
    - improvement in buffering of stream reads in lexical
      analyzer speeds up parsing.
    - compiled files (.tlo) load something like 75% faster.

  - Math:
    - relational functions =, <, >, <= and >= now work
      on sequences of numbers.
    - /= function avoids consing.

  - Sockets:
    - poll is now used for timed out connect and accept;
      select is a fallback if poll is not detected at config time.

  Bugs

  - Sequences:
    - uninitialized memory problem affecting the functions
      in, reverse, find, rfind, pos, rpos and tprint
      when used with vector-like sequences.
    - The function in is also affected when used with
      hashes.

  - Compiler:
    - fixed miscompilation of if form when the test is
      a constant expression that evaluates to false.

  - tags.tl:
    - fixed bug in file opening logic when following (load ...) forms.

  - Printer:
    - symbols with zero-length names now printed with package prefix,
      instead of nothing, so they enjoy read-print consistency.

  - Sockets:
    - broken timed-out connect fixed.

  - FFI:
    - some bugs fixed in carray code after a code review.



                                    TXR 236
                                   2020-04-18


  Features

  - open-file:
    - new "n" mode for non-blocking open.
    - now allows async signal delivery during open so blocking open can be
      interrupted.
  - New touch function, analogous to Unix utility.
  - Unicode:
    - map of characters that need two spaces on the terminal has been updated
    - now includes emoji in the U+1Fxxxx plane.
  - Listener:
    - Tab completion over Unicode identifiers works now.
  - Path testing functions now also accept integer file descriptor.
  - configure:
    - shell identification and re-execution logic in configure script
    - now avoids re-execution if the original shell seems good.

  Bugs

  - ignwarn: fixed neglect to handle warning exceptions
    with multiple arguments.
  - autoloading: definitions now trigger autoload, not only references.
    Otherwise if user code redefines some system entity that as not yet been
    loaded, a subsequent attempt to use that entity will trigger autoload,
    clobbering the user's definition.
  - open-socket-pair: fix broken function.
  - sockets: add missing shut-rd, shut-wr and shut-rw variables that are
    already documented.
  - unwind/signals: fixed signal mask restoring regression that first
    appeared in TXR 230.
  - txr-parse: release deferred warnings if erroring.
  - open-file: when "m" flag is in effect and POSIX open is used,
    use 0666 mode, not 0777, else the file will be created with
    execute permissios if the umask doesn't remove them.
  - regex: fix crash caused by duplicate regex character range.
  - vim: work around bug in Vim that causes it to treat "contains"
    (the name of a TXR Lisp function) as a reserved keyword in the syntax
    highlighting definition.



                                    TXR 235
                                   2020-04-12


  Features

  - Lib:
    - new txr-parse function, opening access to the
      parser for the TXR Pattern Language.
      - used by tags.tl.
    - path testing funtions now accept stream argument.
  - Exceptions:
    - unhandled non-error exception throws now simply
      return instead of terminating.
    - in pattern language unhandled @(assert) with
      a non-error exception behaves as failed match.
  - Parser:
    - more efficient handling of list syntax.
  - Listener:
    - Ctrl-X Ctrl-F command to force submission of unbalanced line.
    - dot file security tests improved.
      - permissions of .txr_history files checked also
      - if permissions on .txr_profile or .txr_history are
        bad, txr checks and diagnoses the user's umask.
  - tags.tl script:
    - now handles txr files: define and bind directives,
      as well as Lisp forms in @(do ...).
    - now follows load forms and processes defpackage.
    - each file read in new temporary package, and
      restores list of packages after each file.
  - Build:
    - Now builds cleanly with -Wextra under GCC 7+.

  Bugs

  - tags.tl:
    - backslashes not escaped in tags file.
    - macro-time forms not handled.
  - configure:
    - quote characters handled in config variable values.
  - Doc:
    - existing lineno argument of read and iread documented.
  - Hashing:
    - flaw in weak hash algorithm leading to spurious retention in situations
      when keys are weak, but values have reference to keys, or vice versa.
    - caused streams and parsers to leak.
  - Pattern Language
    - addressed spurious retention issues, causing memory
      growth proportional to the amount of input scanned.



                                    TXR 234
                                   2020-03-25


  Features

  - New base64url encoding:
    - :frombase64url, :tobase64url filters.
    - base64url-encode, base64url-decode and other functions.
  - Compiler:
    - When a TXR Lisp hash-bang script is compiled, the
      execute permissions are now propagated to the
      compiled file, too.
  - Editing support:
    - tags.tl script can now be compiled by compile-file,
      and no longer scans files twice.
  - GC:
    - small memory support: ./configure --small-mem.
    - reduces start-up footprint and size of incremental
      heap allocations.
  - Listener:
    - All major delete operations now yank the deleted
      text into the clipboard.
  - Hashing:
    - hash-uni function has two useful new functional
      arguments in addition to the join function.
  - Lib:
    - apf and ipf functions take additional arguments
      which are retained and inserted into the apply call.
    - search function now available under the name contains.
      - contains reverses the arguments:
        (search seq it) -> (contains it seq)
  - OOP:
    - more efficient stored argument in method and umethod.
      - (mapcar .(foo 1 2 3 ...) objlist) now allocates one
        special object that stores the 1 2 3 ... args
        compactly, rather than consing a list.
      - more use of this mechanism will be made going forward.

  Bugs

  - Regression in open-process dating to TXR 228.
  - The hash-count value of weak hashes was not maintained
    when the garbage collector removed lapsed entries.
    This was broken from the start; never implemented.
  - tags.tl: correctly take advantage of FTW_ACTIONRETVAL
    on glibc.
  - listener:
    - Del key not copying to clipboard, rendering it
      inequivalent to Ctrl-D.
    - Ctrl-W, when deleting a visual selection and the
      previous word, not recording undo history properly.



                                    TXR 233
                                   2020-03-08


  Features:

  - Lib:
    - crypt function now validates arguments rigorously
      before calling underlying C library function,
      which likes to crash with bad arguments.
    - new meq, meql and mequal functions for testing whether
      left argument is equal to any of the remaining arguments.
    - new assq and assql functions, so TXR Lisp now supports
      Ashwin Ram's (cdr (assq key a-list)) as written.
    - New "cumulative" option type in getopts:
      - multiple occurrences of cumulative option are
        accumulated into a list.

  - Vim support:
    - New utility: tags.tl is a utility for generating Vim-compatible
      tags from TXR Lisp sources.
      - can work in conjunction with ctags: ctags can add
        tags to a file generatd by tags.tl and vice versa.
    - Vim syntax files: the : character is no longer an identifier
      constituent.

  - Cygwin:
    - run and sh functions now use spawnvp instead of fork.

  - Listener:
    - Now appends new entries into .txr_history instead of
      overwriting it, helping uses who have multiple interactive
      invocations of txr.
    - History can be saved early at any time with :save command.
    - If no new lines have been entered when quitting, no
      history saving takes place.

  Bugs:

  - fixed broken inequality string comparison:
    - problem caused by string comparison functions misinterpreting
      the return value of cmp-str, which happens to work in the
      expected way on newer Glibc versions.
    - affected functions were str<, str>, str<=, str>= and less;
      indirectly, anything using any of these by default like
      sort, sort-group and so on.
  - @(line) directive now obtains correct line number
    in horizontal mode instead of zero.
  - chmod tests now work on platforms where sticky bit
    manipulation is restricted.
  - Fixed broken semantics of less comparison for symbols, allowing
    both (less a b) and (less b a) to be false, when a and b are
    different symbols having the same name.
  - Fixed breakage in getopts: processing of short options.
  - Fixed missing fnm-extmatch variable (related to fnmatch function)
    which should be defined on platforms that have FNM_EXTMATCH.



                                    TXR 232
                                   2020-02-09


  Features:

  - POSIX:
    - chmod function now supports symbolic modes of the chmod utility
    - chmod and stat nown work on streams and file descriptors
      - fstat now just alias for the same function as stat
    - added utimes, lutimes functions for updating timestamps
    - added mkfifo function
    - added chown and lchown
    - added rmdir
    - ftw now throws exception on failure
    - new copy-file and copy-files funtions
    - new recursive processing functions:
      - recursive copy: copy-path-rec
        - can copy symlinks, preserve timestamps, perms, ownership
      - recursive chmod: chmod-rec
      - recursive chown: chown-rec
      - recursive delete: remove-path-rec

  - Packages:
    - new merge-delete-package function

  - Build:
    - config.log file no longer generated by configure
    - New reconfigure script is generated
      - run reconfigure to conveniently repeat the same configuration

  - Exceptions:
    - New retry and skip exceptions under restart hierarchy

  - Buffers:
    - file-get-buf now has optional byte count and offset params
    - file-put-buf takes optional offset argument
    - new function file-place-buf: like file-put-buf but doesn't
      truncate if file exists

  - I/O:
    - new mode supported by open-file: "m": open for modification:
      - like "w" but doesn't truncate when file exits
      - E.g. "m+b": open for writing and reading, binary, don't truncate

  - Misc: - ensure-dir returns nil when directory already exists, t otherwise
    - with-resources macro takes multiple cleanup forms for each resource
    - New coded-length function for calculating UTF-8 length of string
    - open-files and open-files* now take an optional mode argument
    - numerous documentation fixes

  Bugs:

  - Fixed regression: @(skip :greedy) broken.
  - FFI: broken handling of undimensioned character arrays
    (no UTF-8 conversion)
  - mknod: third argument now optional, as documented
  - ensure-dir: fail if object exists and is not a directory
  - compiler: bug in compilation of catch form, causing
    "frame level mismatch" exception
  - packages: fixed lack of documented defaulting of package argument in
    several functions
  - copy-file: now detects source object is a directory, and avoids
    creating the target object in that case before failing
  - the internal c_str function now rejects symbolic arguments
    - some functions in TXR that were documented as requiring strings
      had the undocumented feature of accepting symbols, due to this
      behavior of c_str
  - listener now catches exceptions during gathering of completions,
    preventing TXR from bailing in that case
  - fixed incorrect return value of fill-buf and fill-buf-adjust
  - buf-set-length was not consistently setting newly allocated bytes
    to the requested initial value



                                    TXR 231
                                   2020-01-12


  Features:

  - compiler:
    - New function: compile-update-file for compiling
      a file only if necessary.

  Bugs:

  - gc:
    - aarch64 corrupt behavior due to not scanning for
      roots sufficiently far into the topmost (lowest address)
      stack frame.
  - build:
    - problem building on musl: sysif.h header
      referencing undeclared type off_t.
    - build breakage on big endian systems when
      libffi disabled.
    - double definition of FLO_MAX_DIG in config.h
      when configuring under musl.
  - misleading diagnostic when the name of builtin macro
    is defined as a function or vice versa.
  - incorrect FFI test cases (targeting glob function),
    leading to crash on musl.
  - hash:
    - equal-based hashing not traversing the key field
      of a tree node.



                                    TXR 230
                                   2019-12-20


  Features:

  - build: PIE (position-independent executable) builds are disabled.
    - PIE caused a crash in non-local transfer logic.
    - causes an 22% or more penalty on 32 bits x86.

  Bugs:

  - FFI: fixed bug in implementation of newly added zchar type.
  - mitigated crash in non-local control transfer logic (extended_setjmp)
    caused by PIE executable compilation
    - PIE is now enabled in some leading distros.



                                    TXR 229
                                   2019-12-14


  Features

  - OOP:
    - multiple inheritance now supported.
  - FFI:
    - FFI structs now allow initforms in slots.
      - limited evaluation semantics
    - New zchar type for defining arrays char that
      are optionally null terminated.
  - math:
    - hyperbolic functions and their inverses added.
  - buffers:
    - buf-list function: convert buffer to list of bytes.
    - buffers support list ops like car, cdr.
  - getopts:
    - new define-option-struct macro for simplified
      specification of command line options.
  - path testing:
    - new path-dir-empty test for empty directories.
  - disassemble: improvement in output.


  Bugs

  - issue with .? not parsing as a top-level expression.
  - listener: serious bug in balanced line check.
  - intern-fb: bug in optional argument handling.
  - load: wastefully gathered source loc info for .tlo files.
  - OOP: serious stability bug in static slot inheritance logic.



                                    TXR 228
                                   2019-11-19


  Features

  - Syntax:
    - New null-safe slot access operator .?:
      - a.?b means: (if a a.b), with a evaluated once, of course.
      - .?b means (lambda (arg) (if arg arg.b)).
  - Hashing:
    - New hash-invert function for reversing a hash table
      (values become keys and vice versa).
    - New hash-reset function to restart a hash iterator,
      possibly with a different hash.
  - Lib:
    - New identity* function; like identity, but with flexible
      arguments.
  - Expander:
    - expansion now interruptible with Ctrl-C
  - System Interface:
    - stat function now exposes high resolution time stamps.
    - open process supports a new < > syntax in the mode string, for
      arranging file descriptor redirections.
      - E.g. redirect stderr of gcc to stdout, like shell's 2>&1:
          (open-process "gcc" "r>21" '("foo.c" "-c"))
    - new open-subprocess function
      - like open-process but allows caller to specify Lisp funtion to execute
        in child process, before the specified program is executed.
      - executing a program is optional in open-subprocess
  - GC:
    - GC now gives memory back to malloc when all objects in a heap
      block are freed; on GNU/Linux this results in a munmap which
      gives back the memory the OS.
  - Buffers:
    - new functions for buffer-integer conversion: buf-int, buf-uint,
      uint-buf, int-buf.
  - FFI:
    - These carray functions were renamed: carray-unum, carray-num,
      unum-carray and num-carray.
      - "num" changes to "int"

  Bugs

  - Expander:
    - fixed a situation producing bogus undefined variable warnings.
  - Evaluator:
    - bugfix: eval was expanding the form in a null macro environment,
      yielding spurious warnings when eval is used with an eval argument.
    - now expands in a macro environment derived from the passed-in
      eval environment.
  - op macro:
    - Wrongly producing backwards-compatible behavior for compat values
      up to 255, rather than up to 225.
  - System Interface:
    - bugs fixed in path-file-p, path-dir-p, path-symlink-p, path-blkdev-p,
      path-chrdev-p, path-sock-p, path-pipe-p as well as
      path-strictly-private-to-me-p.
    - close-on-exec regression: not setting close-on-exec flag for pipe.



                                    TXR 227
                                   2019-10-26


  Bugs

  - showstopper in configure script



                                    TXR 226
                                   2019-10-25


  Features

  - New data types: binary search trees and their nodes.

  - buffers:
    - now comparable for inequality with less function.
    - convenience functions buf-str and str-buf for
      converting between a string and a buffer holding UTF-8.
  - gc:
    - Heap objects are now more strictly aligned in memory,
      allowing for a faster in-heap test in the garbage collector.
  - hashing:
    - Better use is made of the hash seed for lists and vectors.
    - New feature: eq-based hash tables.
    - Performance improvements: recompile time of the .tl files
      in stdlib improved by 10%.
  - eval & environments:
    - symbol-function supports lambda expressions.
    - accessors now provided for additional function properties:
      - number of fixed and optional args
      - is the function variadic
  - op:
    - new @rec metavar for self reference, allowing anonymous recursion
    - do behavior revised in light of mismatch between documentation
      and implementation.
    - new macro ldo: version of do that inserts left argument.
  - lib:
    - copy-cons now copies lconses and is more efficient.

  Bugs

  - Build: added forgotten "alloca.h" header into version control.
  - Improved overflow detection in string catenation.
  - gc:
    - fixed bug in heap bounding box calculation, making
      the in-heap test less efficient.
  - func-get-name: bogus return for nil argument.
  - stdlib: numerous incorrect uses of compile-error.
  - circle notation:
    - on read, not handling circular refs in hash userdata.
  - lib:
    - memory leak in bit function.
    - fixed buggy type tests that application code could subvert.
    - affects hashes, carrays, random-state objects, regex char sets and
      struct types.
  - hash:
    - use unsigned type ucnum consistently for hash values.
    - do not negatively index into hash table vector.
    - traversal limit observed when traversing keys that are vectors
      and hashes.
    - strings keys now subject to traversal limit, at a rate of 4:1:
      four characters count as traversing one node in the object graph.
  - eval:
    - eval function wrongly passed eval environment to macroexpand.
  - lib/vm/compiler:
    - not handling excess number of function arguments, leading
      to overflow in the fixparam field in the function object.



                                    TXR 225
                                   2019-09-11


  Features

  - Lib:
    - tailp function added
    - Unicode BOM character object now prints as #\xFEFF rather than
      #\ followed by a literal zero-width non-breaking space.

  - OOP:
    - cons cell used in non-cached slot lookup now recycled.
    - access to common special methods like length now optimized.
    - objects with length or car method now recognized as subtypes
      of sequence.

  Bugs

  - Interpreter:
    - issue between in let* and continuations: copy-env throws error.

  - list-builder:
    - significant rewrite of some internals.
    - fixed broken self-appending and deviation from append semantics.

  - Type system:
    - subtypep now reports string and lcons as subtypes of sequence.
    - objects with only length method now reported as sequences.

  - Lib:
    - Incorrectness in digits and digpow functions.
    - bracket function incorrect when some or all arguments
      passed via apply mechanism.



                                    TXR 224
                                   2019-08-29


  Features

  - compiler:
    - load-time now optimized away if top-level form.
      - argument of load time top-level form if load-time is
    - improved code generation for destructuring.
    - case of wasteful nil-initialization of local variable elided.

  - lib:
    - list-builder now has dequeue capabilities:
      - delete item from head and tail
      - new buildn macro to complement build:
        - returns last form instead of constructed list
    - new functions find-symbol, find-symbol-fb:
      - find symbol in package, with or without fallback lookup.
    - new function intern-fb:
      - like intern, but with fallback lookup.
    - new function cptr-buf:
      - obtaining cptr object referencing buffer contents.
    - MD5 digest support.
    - State-object-based, multi-step SHA-256 and MD5 digesting.
    - More efficient SHA256 string hash (not using string-byte-input stream).

  Bugs

  - lib:
    - regression in where function: not working for non-list sequences.
  - parser:
    - symbols no longer interned within object suppressed by #; notation.
    - uninitialized flag field in parser structure:
      - affects TXR 157 through 223.
      - affects circular notation like #1=(#1#) embedded in the
        pattern language.
    - cosmetic issue in bad character diganostics from lexical analyzer.
  - build:
    - remove_flags configure option was broken;
    - compiler flags were duplicated in the commandline.
  - unwind:
    - GC problem: neglect to GC-protect global unhandled-error structure.
  - compiler:
    - miscompilation of infinite for loop: (for init (nil) step ...)
      - where terminating condition is explicitly given as (nil ...)
        rather than implicitly as ().
    - destructuring:
      - error mismatch diagnostics indicating wrong substructure.
      - inappropriate special handling of colon args to optional params.
      - incorrect scoping for optional param init-forms in destructuring.
  - trace:
    - failure to remove trace from traced function being redefined.
    - redefinition of a traced method resurrects old version, clobbering new.



                                    TXR 223
                                   2019-08-14

                             Celebrating Ten Years!

  Features

  - Pattern Language:
    - small performance improvement in @(collect) and @(coll)
    - important semantics improvement in :vars feature of @(collect)/@(coll).
  - lib:
    - base-name now takes second optional argument: suffix to strip away.
      - just like POSIX basename command
  - compiler:
    - better code generation for immediately-called lambda
    - improved code from pop macro
  - listener:
    - faster history saving due to taking advantage of buffered I/O
      instead of flushing each line.

  Bugs

  - Fixed issues in compilation of immediately-called lambda:
    - incomplete optional parameter support.
    - evaluation order problems.
    - subtle scope problems.
  - reverse function no longer complains about a #<garbage ...> object
    when given an unsuitable argument.
  - added missing autoloads for a number of macros:
    - test-set, test-clear, compare-swap, test-inc and test-dec
    - because of the way compilation of the library works, these
      documented operators were unavailable even when their containing
      module was loaded due to some other symbol.
  - fixed regression: lack of file and line number reporting for
    unbound variables.



                                    TXR 222
                                   2019-07-30


  Features

  - FFI:
    - type.a.b.c syntax for navigating struct and union types.
      - for instance given (struct foo (x int)):
        - foo.x denotes int
        - (sizeof foo.x) is same as (sizeof int)
    - elemtype is a type operator now, not only macro:
      - (struct foo (x int) (y (elemtype foo.x))) declares y of type int.
    - elemsize and elemtype work on enums.
      - worked previously, now documented.
    - structs and unions may now be self-referential:
      - (struct foo (datum int) (next (ptr (struct foo))))
      - type system will convert a Lisp linked list to C, and vice versa.

  Bugs

  - FFI:
    - null pointers handled in "in" operation:
      - e.g. when struct argument passed into a C function contains
        pointer that is nulled out.
        - struct is converted back to Lisp.
  - parser:
    - fixed failure to pinpoint start of unterminated expression,
      when it starts on line 1 of the stream.



                                    TXR 221
                                   2019-07-23


  Features

  - FFI:
    - Structures with flexible array at the end ("flexible structures")
      are now supported.
    - FFI types now have a dynamic size.
      - this can be explored with two-argument form of sizeof operator,
        which takes a prototype Lisp object as an argument.
        - (sizeof (array uint32) #(1 2 3)) -> 12.
    - Previously undocumented ffi-out function is now documented.
  - hashes:
    - New hash-zip function for constructing a hash from
      a separately given sequence of keys and sequence of values.
  - lib:
    - relate function optimized with hashes.

  Bugs

  - FFI:
    - Buffer operations ff-put and others now work with variable length arrays
      instead of accessing out of bounds.
  - TXR:
    - Fixed 2019-04-21 regression causing the file name to be missing
      from error messages.



                                    TXR 220
                                   2019-07-08


  Features:

  - New make-byte-input-stream function for abstracting byte streams
    creation over objects of different kinds.
  - sha256:
    - program can specify buffer where sha256 is placed to avoid
      allocating a new one.
  - sha256, crc32:
    - stream hashing operations internally use recycled I/O buffer.
  - New function buf-put-buf: more efficient way to plant one buffer's
    contents into another.

  Bugs

   - @(define): fixed problem in parametr list code walk, leading to spurious
    undefined variable warnings.
   - @{var1 var2}: fixed November 2011 regression: not working when var2
     is bound to a regex or string list.
   - Broken carray-replace repaired.
   - overlapping use of replace family of functions:
     - semantics addressed in documentation
     - implementation fixed to avoid overlapping memcpy
   - compile-file:
     - no longer silently ignores top-level forms that are atoms or that
       macro-expand to atoms.
     - top-level atoms are compiled to produce diagnostics; then
       the compilation result is discarded.



                                    TXR 219
                                   2019-07-01


  Features

  - Base64 functions now work on buffers.
  - New sha256 and crc32 functions.
  - Sequences improvements:
    - numerous internal changes for better maintainability and performance
    - buffers and carrays considered sequences
      - (append #b'...' #b'....) works
      - nconc ditto
    - nullify function handles hashes, buffers and carrays
    - empty function handles buffers and carray
    - in function allows testfun and keyfun on hashes
  - defset now provides temporary variable for store value, so store form
    doesn't have responsibility of once-only evaluation.

  Bugs

  - lnew: two regressions fixed.
  - at-exit-do-not-call: logically reversed return value fixed.
  - seq-begin: due to bug, worked only with lists.
  - :key parameter macro: fixed bug causing key values to go to
    wrong variables.
  - various macros that use the constantp function were calling it
    with a null environment.



                                    TXR 218
                                   2019-06-19

  Features:

  - Lib:
    - new hash-peek function.
    - New seq-peek function for peeking at next item in iteration.
    - Sequence functions sub, replace, and their list, vec and
      str specializiations have been substantially rewritten to
      tighter semantic specifications.
      - The sub- functions are also all accessors now.
    - cat-str, split-str and spl now accept character object as separator.
    - New bitset function for breaking integer into bit positions.

  - FFI:
    - sub-buf accessor and replace-buf function introduced.
    - Semantics of variable length zarray made more sensible.
    - carray-sub accessor is improved; the syntactic place works
      via carray-replace, rather than generic replace.

  - Compiler:
    - A "--lisp" argument in the hash bang line of a source file
      is translated to "--compiled" in compiled file's hash bang line.

  Bugs:

  - Command line:
    - regression: unsuffixed hash bang script wrongly treated as Lisp.

  - Lib:
    - Multiple bugfixes in replace-list, such as negative indices
      in index list assignment now follow the usual convention.
    - select function handles negative indices; internals rewritten.
    - logcount crashing for fixnum arguments on 64 bit builds.

  - FFI:
    - carray-replace now performs index list assignment like
      other replace functions.
    - carray-refset now allows negative indices, with usual conventions.
    - buffers likewise support negative indexing.

  - GC:
    - stability issues fixed in make-struct, make-package and
      the arithmetic function ash.

  - Expansion:
    - Several hygiene bugs fixed in defset.



                                    TXR 217
                                   2019-06-10

  Features:

  - Integrated POSIX fcntl function, supporting
    F_SETFD, F_SETFL and F_SETLK.
  - errno constants are now provided.
  - POSIX close function added.
  - Windows installer associates .txr, .tl and .tlo suffixes with the
    txr executable.
  - fixnum range now includes the most negative two's
    complement value that fits into its representation,
    rather than excluding it.
  - place macros: slight adjustment to expansion strategy.

  Bugs:

  - Fixed failure to handle most-negative integer value in situations
    when a Lisp integer is converted to a fixed C integer.
    - Fixes a regression in the minimal Windows program example, in which
      (defvarl CW_USEDEFAULT #x-80000000) appears.
  - path-private-to-me-p function was considering superuser as
    just another user
    - properly locked down root-owned file was not considered private.
    - same with path-strictly-private-to-me
  - list length: off-by-one error for huge lazy lists that overflow
    a pointer-wide counter.



                                    TXR 216
                                   2019-05-20


  Features

  - Doc: .cblk/.cble replaced by .verb/.brev and .mono/.onom.

  - Debugging:
    - crude debugger removed
    - work under way for new debugger
    - backtraces for interpreted code, enabled by --backtrace

  - Exceptions:
    - new catch** macro which provides a description of each
      clause

  - I/O and system interface:
    - Streams support third variant of indentation: "force indent off".
    - Streams support depth and length limitation on objects.
    - More nuanced exceptions: exception types distinguish permission
      from non-existence and other errors.

  - OOP:
    - New function, allocate-struct: no frills, fast allocation
      of instances.
    - New function struct-type-name.
    - New macros new* and lnew*: these evaluate type expression.
    - New "derived hook": a class function called derived
      is invoked when a class is the target of inheritence.

  - Lib:
    - Substring operation no-op case now returns original string
      instead of copying.
    - New window-mapdo function: non-accumulating window-map.

  - System:
    - New cptr-size-hint function informs the garbage collector of
      the size of a foreign array.
    - load function now tries suffixed versions of path first,
      (.tlo followed by .tl) then falls back on trying unsuffixed.
    - *load-path* is bound to the actual path used to open the file,
      rather than the unsuffixed input path.
    - compile-file now resolves relative paths relative to existing
      *load-path* value, just like load does.
    - it is documented that compile-file sets *load-path*.
    - Input file search strategy of compile-file is harmonized
      with that of load.

  Bugs

  - tagbody: code replication bug leading to excessively
    large translation instead of jumps into single code vector.
  - issue in interaction between @(output) and lazy-list-valued variables.
  - MPI: floating-point math eliminated from radix length calculation.
  - compiler:
    - bug leading to "frame level mismatch" in VM execution.
    - triggered by special variables used as optional parameters in lambda.
  - build: allow $(pwd)/configure to work.
  - long-running regression in apply function has been fixed.
  - parser: line numbers off by one for hash bang files.



                                    TXR 215
                                   2019-03-30


  Features

  - Math:
    - User-defined arithmetic types are now possible.
      - objects which implement certain methods accoring to the
        documentation can be passed into arithmetic functions.

  Bugs

  - Listener:
    - we now ensure that the .txr_history as well as the temporary
      files created by the Ctrl-X E command (edit in external editor)
      are readable only to the user: perms rw-------.



                                    TXR 214
                                   2019-03-22


  Features

  - Improved expt function
    - raising integers to negative integers works.
    - raising zero to negative exponents throws division by zero.

  - Floating-point error checking
    - Infinity and NaN results are turned into exceptions rather than
      propagating as #<bad-float>

  - New generic sequence iterator objects.
    - seq-begin, seq-next

  - Function where becomes lazy.

  - Optimization in various lazy list processing functions.

  - Lazy cons improvements:
    - New lcons-car and lcons-cdr functions can access
      fields in a lazy cons without triggering the update function.
    - make-lazy-cons takes two optional arguments to initialize
      the car and cdr fields
    - thus, propagation of state in lazy list generation can use
      the lcons itself as temporary storage.

  - OOP:
    - Type struct introduced:
      - all struct instances have struct as a supertype

  Bugs

  - Parser:
    - out of range floating-point tokens now trigger error
      rather than turn to nil.



                                    TXR 213
                                   2019-03-08


  Features

  - new load-for function:
    - loads another module conditionally on a variable,
      function, struct or package not being defined.

  - listener:
    - input limit raise from 1023 to 4095 characters.

  - new defset macro:
    - like defsetf in ANSI CL; define function-like syntactic places easily.

  Bugs

  - listener:
    - fixed some lingering line wrap glitches in optimized
      character append logic.
    - fixed buffer overflow when loading history, when lines
      are too large for the maximum input length.
    - fixed hang when evaluation produces cirular object,
      even though *print-circle* is on.

  - library symbol regression:
    - two library symbols regressed into the sys package: the --
      delimiter in :key parameter lists and the lnew (lazy new)
      for instantiating structs lazily.

  - disassembler:
    - operands of getlx, setlx instructions disassembled wrongly.

  - compiler:
    - fixed two cases of incorrect handling of lambda expressions
      that are immediately called.
    - fixed (fun (lambda ...)) operator yielding an interpreted function,
      even though it's compiled.

  - core semantics:
    - lambda expressions are no longer fboundp.
    - incorrect macro environment handling when expanding tree-bind.



                                    TXR 212
                                   2019-02-24


  Features

  - OOP:
    - more efficient new operator: now avoids extraneous consing.

  - Printer:
    - changed conditions for when symbols are printed with a package
      prefix.
    - the code is also optimized, and handles more cases when symbols
      should be printed with the #: uninterned prefix.

  - Lib:
    - pprof macro generates much smaller code.
    - faster "highest bit set" calculation, using GCC primitives.
    - new bracket function.

  Bugs

  - GC:
    - fixed GC bug in the parser, in relation to parsing circular notation.
    - fixed GC bug in clearhash function.
    - fixed two GC bugs in FFI: in the enum type and cptr type.

  - Compiler:
    - Fixed miscompilation of (prof <form>) in cases when <form>
      is known at compile-time to return nil.

  - Listener:
   - Fixed hang issue that occurs when evaluation produces a circular
     object even though *print-circle* is turned on.
   - Fixed Ctrl-X Ctrl-P not being mentioned in the "cheatsheet".



                                    TXR 211
                                   2019-02-18


  Features

  - App delivery:
    - new function save-exe.
    - new txr-exe-path variable.

  - Regex:
    - new functions scan-until-match and count-until-match, related
      to read-until-match (scanning for regex inside I/O stream).

  - Lib:
    - new functions fill-buf-adjust and buf-alloc-size.

  Bugs

  - GC:
    - Objects on which finalizers were invoked were being retained until the
      next full GC, instead of being reclaimed at the next incremental GC.

  - Listener:
    - Fixed buffer flow in reading external file.
    - When editing in external editor, preserve the file if it is too large
      to be read back into the command line.
    - Fixed vertical skip problem in multi-line mode, related
      to the recent regressions.

  - OOP:
    - When struct types are removed, their IDs are now recycled, preventing
      struct ID exhaustion.



                                    TXR 210
                                   2019-02-14


  Features

  - Hashing:
    - New functions hash-symdiff (symmetric difference) and hash-from-alist.
    - Performance optimizations.

  - Library:
    - diff, isec and uni work efficiently for non-list sequences, and
      support hashes.
    - New function symdiff (symmetric difference).

  Bugs

  - hash-uni was wrongly calling the join-func also for keys that are only in
    the left hash, rather than just keys that are in both hashes.
  - Listener regression in TXR 209: hitting Enter in multi-line mode causes
    ^M to appear instead of advancing to the next line.



                                    TXR 209
                                   2019-02-08


  Features

  - Compiler:
    - string literals and bignums now de-duplicated in compiled files.
    - caseql generates slightly better code in the integer jump table case.
    - new function dump-compiled-objects
      - allows applications to programmatically generate compiled files
        out of individually picked compiled forms.

  - Library:
    - The sum and prod functions now take an optional keyfun argument.
      - Example: add up sizes of "*.txt" files:
          (sum (glob "*.txt") [chain stat .size])

  Bugs

  - Compiler:
    - The defvar/defparm macros didn't take into account compilation, only
      marking the symbol special at expansion time, but neglecting to emit the
      code to do that when the expansion is executed.
      - This works for interpreted code, of course, but under compilation it
        means that if we compile a (defvar x) in a file with compile-file, the
        resulting compiled file will produce a global lexical x, not a
        dynamically scoped x.

  - Build:
    - The library is no longer compiled twice: the .tlo2 files are gone.
      - The idea that there could be a legitimate difference in the files
        compiled by a partially-compiled image, versus a fully-compiled image
        was wrong-headed. They are in fact the same, unless there is a bug.
        The interpreted compiler must produce the same results as the compiled
        compiler, period.
      - In fact, there was a difference between the "stage1" and "stage2"
        compiled files: it was caused by the above defvar bug.

  - Pattern Language:
    - When a call to a user-defined @(function ...), all on a line by itself
      (vertical mode) faces the end of input (EOF), the function was not being
      called.
    - Functions were able to shadow horizontal directives.

  - Listener:
    - November 2018 regression that caused screen update glitch when a long
      line wraps.
    - The caret notation ^@ was not used for the NUL character; it was sent to
      the terminal as-is (ignored by most terminals), but counted by our editor
      as having a display width of 1.
    - The ^@, ^A, ... caret notation was not being used for control characters,
      when these were inserted at the end of the line in the optimized
      no-refresh case.

  - Parser:
    - In string literals, handle embedded byte properly, mapping it to \pnul.
    - In string literals, diagnose bad UTF-8.

  - FFI:
    - make-zstruct/znew were blowing up when the FFI struct type has padding
      slots, indicated by the symbol nil.
    - deffi-cb-unsafe macro was not being auto-loaded.
    - ffi-make-closure's safe-p parameter's defaulting was mishandled, causing
      it to be always true even when given a nil argument.
      - thus deffi-cb-unsafe behaved like deffi-cb.
    - In FFI closure dispatch, clear previous state related to exception
      handling, which covers situations when we return to foreign code
      due to an exception, but the foreign code calls down again into
      a closure rather than itself bubbling up to Lisp.



                                    TXR 208
                                   2019-01-28


  Features

  - The -f command line option can be used with the Hash Bang Null Hack.

  Bugs

  - Showstopper bug in copy-hash also affecting hash-diff.
  - Pattern Language:
    - Bug in @(next) directive's :nothrow
      - @(next "file" :nothrow) wrongly reading from standard input
        if opening "file" throws.
    - @(next expr :nothrow) not catches error exception
      thrown by Lisp code.
      - The documentation can be interpreted as requiring this
        and the expectation is intuitive.
      - Same with @(next :list <expr> :nothrow) and
        @(next :string <expr> :nothrow).



                                    TXR 207
                                   2019-01-26


  Features

  - Internal code structure and performance improvement in the areas of FFI,
    integer types and bignums.

  Bugs

  - FFI: fixed bugs in the be-int64 and le-int64 types,
    making these usable.
  - Build problem: "make install" failing for compiled .tlo
    files when using a separate build directory.



                                    TXR 206
                                   2019-01-18


  Features

  - deffi, deffi-var and deffi-sym macros now helpfully diagnose if they
    require a surrounding with-dyn-lib macro that is missing.

  Bugs

  - fixed bugs in vec-carray and list-carray functions.
  - fixed bug in addition involving a bignum and small integer.
  - fixed bug in random and rand function: not generating values
    over the full range specified by the modulus.



                                    TXR 205
                                   2019-01-15


  Features

  - New function square for squaring a number; faster for bignums.
  - FFI:
    - array handling is more forgiving: Lisp sequences shorter than the array
      can be converted without error; the array is null padded.

  Bugs

  - build:
    - fixed problem related to alloca.h, reproduced under the Musl C library.
  - compiler/assembler:
    - fixed several bugs that prevent the compilation of functions with
      deeply nested lexical scopes or large numbers of local variables,
      yet well within the VM limits.
  - FFI:
    - Fixed issue in (array n char) type's put operation: this FFI type
      does not null-terminate, but was doing it when truncating strings
      longer than n.



                                    TXR 204
                                   2018-12-18


  Features

  - New function nzerop: negates zerop so we don't have to
    write (not (zerop x)).
  - Turning off -fstack-protector gcc option foisted by some distros
    - improves VM performance about 7% in loop benchmark.

  Bugs

  - defvar:
    - fix variable being in a state of limbo if the
      initializing expression throws.
  - build:
    - we were ignoring the LDFLAGS variable from
      the make command line or environment.
  - character handling:
    - fix UTF-8 decoder bug causing failure to decode four-byte
      sequences correctly.



                                    TXR 203
                                   2018-11-29


  Features

  - Optimizations in vm.
  - pprint keeps colon on keyword symbols.
  - New functions in-range, in-range*.

  Bugs

  - logxor: broken function fixed.
  - caseq*/caseql*/casequal*: fixed broken handling of
    clauses containing multiple keys: (caseql* x ((a b ..) ...)).



                                    TXR 202
                                   2018-11-22


  Features

  - Some optimizations in arithmetic library, compiler and virtual machine.
  - New function copy-fun:
    - copies functions, making a duplicate of their environment.
    - can take a "snapshot" of a closure.

  Bugs

  - compiler:
    - compile function now correctly handles functions that carry a lexical
      environment.
      - interpreted environment gets compiled into VM environment.
  - Build issue upstreamed from Void Linux distro:
    - On Musl library, <sys/select.h> header is required for fd_set.



                                    TXR 201
                                   2018-11-07


  Features

  - load now tolerates and ignores hash bang lines instead of
    trying to parse them as syntax.
    - previously, hash bang was only supported in files invoked
      from the txr command line.
  - some internal improvements related to gc.
  - improved type mismatch diagnosis in many library areas
    - more instances of which function triggered mismatch.

  Bugs

  - compiler:
    - compile-file was incorrectly handling situation with a defpackage
      followed by symbols from that package in the same file,
      resulting in a file that won't load.
  - load:
    - exception no longer thrown when file is empty.
  - a few instances of error messages containing a quoted
    function name.



                                    TXR 200
                                   2018-11-05


  Features

  lib:
  - The form expander is now a public, documented feature,
    including expand-with-free-refs, which informs about free variables
    occurring in a form.
  - New copy-buf function, called by copy for buf objects.

  compiler:
  - Better code generation for dwim forms.
    - global functions and global lexical variables in dwim
      forms are handled more efficiently.
      - no more lisp-1-style dynamic lookup at run-time; compiler resolves
        references to function or variable bindings.
    - a global function in the first position is dispatched the same as a
      regular call, resolved at compile time to the function binding; so
      [mapcar list '(1 2 3)] generates exactly the same code as
      (mapcar (fun list) '(1 2 3)) using the gcall instruction.

  listener:
  - performance improvements in multi-line edit mode:
    - refresh operations are avoided for cursor movements, incomplete line
      warning flash, and character appends at the end of the line.
    - much better copy and paste experience, and better experience on
      slow/lagged remote connections and serial lines.
  - uses temporary file for saving history.

  doc:
  - HTML table of contents "collapse all" logic doesn't
    hide the entire table, keeping the major sections visible.

  Bugs:

  - listener:
    - fixed abort on window resize (regression from Unicode work
      earlier in the year).
    - history now saved using temp file which is renamed after
      being successfully written.



                                    TXR 199
                                   2018-10-28


  Features

  - compiler:
    - hash bang in source files translated into compiled files.
    - more constant folding optimizations in equality comparisons.
    - de-duplication of code when compiling switch form whose branches
      share source code substructure (the basis for tagbody).
    - faster access to global lexical variables via two new VM instructions.
    - semantics change in handling of free variables:
      - undeclared variables treated as lexical rather than special.
      - defvar/defparm now warn if the variable was already used.

  - OOP:
    - improved diagnostics in uslot and umethod.

  - math:
    - new function random-float which produces evenly-distributed
      pseudo-random values in the range [0, 1).
    - functions exposed for floating-point rounding control.
    - new signum function.

  - lib:
    - list-builder methods rewritten for semantics and efficiency.
    - op-related macros rewritten in Lisp.
    - hashing function for floating-point values rewritten for efficiency.

  - evaluation:
    - top level forms under evaluation and compilation handled
      incrementally:
      - thus: if (prog A B) is a top-level form, then A will be
        macro-expanded and evaluated before B, so B can rely on
        A's expansion and compile-time effects to have occurred.

  Bugs

  - compiler:
    - fixed miscompiled empty test in for loop.



                                    TXR 198
                                   2018-07-06


  Features

  - Hashes:
    - Hash tables and the hash-equal function now use a hashing function keyed
      with a seed, providing a tool against hash collision DoS attacks.
    - New *hash-seed* special variable, gen-hash-seed function.
    - make-hash and hash-equal take optional seed argument.
    - hashes implicitly take their seed from *hash-seed*, which is initialized
      to zero (for repeatability).
    - seeding hashes is the application's responsibility; TXR will not
      automaticaly seed hashes.

  Bugs

  - Listener:
    - crash in selection yanking. This regression is
      a result of the recent "unicodization" of the listener.
  - VM:
    - compiled code now follows the situation when a function binding
      is deleted with fmakunbound and then a new binding is introduced
      for the same symbol.
    - source location info is no longer wastefully recorded for the forms
      that occur in compiled files.
  - Hashes:
    - equal function broken comparing two hashes: incorrect logic.
    - copy-hash not copying equal function pointer, causing garbage
      function pointer to be dereferenced when copied hash is
      compared for equality.
  - POSIX interface:
    - ftw funtion discovered broken (from initial implementation).
      Callback mechanism allocated four words on the stack, then
      put five arguments there. This was previously undetected, but
      recent improvements in args handling now caused ftw to assert.
  - Awk macro:
    - fixed nonworking (next); a regression caused by the Lisp compiler
      optimizing away (block ...) construct.



                                    TXR 197
                                   2018-05-27


  Features

  - logcount function:
    - counts one bits in non-negative integers, zero bits in negative ones.
    - closely based on ANSI CL logcount.

  Bugs

  - listener:
    - regression in 196: fatal exception if .txr_history
      file doesn't exist.
  - compiler:
    - failure to handle block* special form, and therefore also tagbody.
  - awk:
    - autload issue: compiled file containing awk expression won't load.



                                    TXR 196
                                   2018-05-18


  Features

  - Both the TXR Pattern Language and TXR Lisp now allow Unicode
    in identifiers.
    - Un-braced variables like @abc in the pattern language and
      string quasiliterals are excluded from this change.
    - Braced variables and Lisp symbols, including packag prefixes,
      may use Unicode characters.
    - Unicode spaces cannot be used in identifiers, and neither can
      various invalid characters.
  - The Interactive Listener now supports Unicode input.



                                    TXR 195
                                   2018-05-04


  Bugs

  - Overhaul of handling of parameters that are special variables.
    - was not implemented at all in interpreted destructuring.
      - compiled destructuring implemented it by using let.
    - had subtly wrong scoping semantics, not affecting most code.
    - was broken completely due to a regression in TXR 190
  - MacOS and Solaris ports:
    - fixed broken method for getting TXR's executable path, which
      caused TXR not to work unless invoked via full path.



                                    TXR 194
                                   2018-04-30


  Bugs

  - FFI:
    - issue causing inability to to encode the most negative signed
      32 bit integer on 32 bit platforms, and the 64 bit one on 64
      bit platforms.
  - compiler:
    - fixed situations when compiler generates immediate move instructions
      for integer operands that are too wide to be used as immdiate literals.
  - assembler:
    - fixed a situation in which a bignum integer was encoded as a literal
      using its bitwise pointer representation.



                                    TXR 193
                                   2018-04-26


  Features

  - compiler:
    - load-time special form, similar to load-time-value in ANSI CL.
      - evaluates an expression on file load whose value is treated as a
        literal object.
      - program doesn't have to define a top-level variable; load-time occurs
        anywhere in code.
    - code improvement in translation of
      - string quasiliterals
      - destructuring (tree bind, macro arguments, ...).
    - compiler now removes (block ...) constructs that look as if they are not
      needed.
  - vm:
    - big improvement in stack usage of running VM.
    - addressed some spurious retention issues.

  Bugs

  - autoload
    - fixed programs experiencing errors due to some library modules not
      loading.
      - caused by situations when the dependency from a library module A to B
        modules was keyed only to the macros provided by B, not B's run-time
        functions generated by the macros.
      - of course, compiled code doesn't refer to macros any more.
  - compiler:
    - fixed (return x) being mis-compiled as if it were (sys:abscond-from nil x).
  - awk: fixed multiple expansion of path/command argument in I/O redirection
    macros ->, ->>, <-, !> and <.



                                    TXR 192
                                   2018-04-19

  Features

  - compiler:
    - compiled files now marked with byte order indication
      - TXR compiled on big-endian will load compiled files made by TXR on a
        little-endian machine and vice-versa.
    - caseq/caseql/casequal optimized to table dispatch for characters and
      integers in dense range.
    - inline lambdas (lambdas that are immediately invoked) are now open-coded
      into let-based binding blocks.
  - parser:
    - Unterminated form errors now show the starting line number of the
      top-level form being read.
  - VM:
    - architectural change: display max depth reduced from 256 to 64 frames,
      but frames with maximum widened from 256 words to 1024 words.
    - object file major version bumped from 0 to 1:
      - compiled files from TXR 191 won't load.
  - lib/VM:
    - wasteful consing eliminated from apply function.
  - continuations:
    - documented differences in compiled vs intepreted behavior with respect to
      mutated lexicals.
    - new macros hlet and hlet* provided for binding lexical variables that are
      based in off-stack storage that isn't captured in continuations.

  Bugs

  - compiler:
    - fixed miscompilation of unwind-protect.
    - missing ((lambda ()) ...) call forms now handled
      - also optimized by open-coding.



                                    TXR 191
                                   2018-04-10


  Features

  - TXR Lisp now has a compiler and virtual machine.
    - individual forms and functions can be compiled
    - TXR Lisp .tl files can be compiled into .tlo object files
    - the Lisp parts of the library are now compiled.
      - TXR starts up some 3.5X faster when most of the
        library auto-loading is triggered.
  - Library:
    - new bignum-len function; get the "size" of a bignum efficiently.
    - ldiff function redesigned with more nuanced semantics.
  - Symbols/Packages:
    - package-prefix-interning now allowed in packages that have a
      fallback list.
    - application code is now read in a package called pub, not in
      the usr package.
    - usr package is devoid of spurious symbols; the Lisp library is
      read in the sys package.
  - Macros:
    - defmacro forms are no longer hackily evaluated at macro-expansion time:
      - evaluated normally, in apparent lexical env.
      - code which does things like:
        (progn (defmacro foo ...) (foo ...)).
        now requires (macro-time ...) around the defmacro.
    - optional parameters in macro-style parameter lists no longer support the
      colon hack for explicitly specifying a missing parameter.
      - only function calls have this feature now.
   - Printer:
     - improved line breaking of aggregate objects.
     - new function force-break exposed, related to this.

   Bugs

   - buffers: buf-get-* functions were not allowing the last byte of a buffer
     to be extracted.
   - structs: post-inits and finalization registrations are now correctly
     performed by reset-struct.
   - trace: several bugfixes in method redefinition check.
   - bignums: fixed broken single-digit bignum multiplication.
   - functions: fixed regression in function argument processing causing the
     failure to diagnose too many args.
   - expander: fixed neglect to add sequentially-bound variables to the
     expansion-time environment when they lack an init-form.
   - expander: fixed some neglected expansions in the sys:for-op special
     operator that implements the iteration forms like each and for.
   - expander: bugs/regressions in handling nil in parameter list expansion.
   - expander: optional parameters of functions were not being expanded in an
     environment in which the previous params are visible.
   - listener: fixed poor treatment of regex syntax in the code which prevent
     lines from being submitted when they
     are ill-formed.
   - gc bugs: fixed some incorrect mutations that break generational gc.
     - some in struct code
     - some in datagram socket code.
   - tagbody: fixed; was broken due to a regression.
   - packages: read/print consistency issue related to packgage prefixes fixed.
   - regex: read/print consistency problem related to double quote.
   - regex: double-free corruption bug related to use of canned
     character classes like \w.
   - hash: fixed broken with-hash-iter.



                                    TXR 190
                                   2018-02-18


  Features

  - Annoying limitation removed: lisp load now handles .txr files.

  - Listener:
    - new *listener-pprint-p* variable turns on use of pprint for
      evaluation results.
    - new *listener-greedy-eval-p* variable turns on a cascaded
      evaluation: values are subject to additional rounds of evaluation,
      whose results are also printed.


  Bugs

  - fixed bug "unbound function sys:l1-val" when using lop operator.
  - fixed expander bug causing (do set [@1 x] y) to be wrongly expanded.
  - autoload bugfix: symbols used for struct slots in standard library modules
    are now interned even if those modules are not loaded, so that they are
    treated properly under the package system.



                                    TXR 189
                                   2018-02-06


  Features

  - read and iread no longer record source-code location info
    unconditionally
    - now controlled by new *rec-source-loc* special variable.

  - OOP:
    - better abstract sequence support:
       - new: special methods rplaca and rplacd.
       - sub and replace function now redirect to lambda and
         lambda set methods.
       - car and cdr fall back on lambda method now if
         object has no car or cdr method.
       - refset defined for objects that have car method.

  Bugs

  - Fixed regression in read-print consistency of hash tables.
  - Fixed bug in sequence classification logic that caused
    objects to be reported as non-sequences.
  - Fixed nthcdr continuing to iterate up to n even after
    end of list reached.
  - Fixed neglected autoload registration for socket functions.
  - Fixed bug in source location recording, causing errors in
    code to be rported against incorrect file names and line
    numbers.



                                    TXR 188
                                   2017-12-19


  Features

  - New funtion grade
    - like grade up/down operators in APL.
    - returns indices into sequence in sorted order.
  - New macro feature: lexical macros can decline expansion.
    - lexical macro can decline to expand by returning original form.
    - lexical scope is searched outwards to find and try another macro.
  - Big hash change:
    - hash function now defauilts to :equal-based.
    - :eql-based keyword specifies hashing based on eql.
    - functions which take hash arguments follow suit: group-by, etc.
  - Streams new feature: structure delegate streams
    - OOP interface for creating objects that substitute into
      stream I/O operations.
    - stream-wrap base implementation for easily wrapping and
      adapting streams.
  - New functions rlist and rlist*: express discontinuous ranges easily.

  Bugs

  - append* and mappend*:
    - fixed unintentional, undocumented destructive behavior
    - fixed non-termination on infinite lists.
  - tail function now handles improper lists.
  - macro expansion bug fixed:
    - neglect to expand the output of a declined macro
    - must be treated as a function call or possibly a special operator
      - either way, may have constituent expressions that
        need expansion
  - prof: deal with overflowing performance counters.
    - we use a 64 bit type if we have it, and convert to bignum
      if and when required.
  - trace: fixed spurious "previously traced" warning on methods.



                                    TXR 187
                                   2017-11-18


  Features

  - Functional library:
    - lop:
      - "left op": new variant of op macro.
      - inserts free arguments on left rather than right.
  - Control flow library:
    - caseq, caseql and caseql expand to better code.
  - Sequences library:
    - find, find-if, find-max, pos, pos-if, pos-max, posq, posql, posqual,
      rfind, rfind-if, rpos, rpos-if, rposq, rposql and rposqual:
      - rewritten with optimization for vectors and strings and proper support
        for vector-like struct objects.
  - Awk macro:
    - five new range operators
    - some optimizations
  - FFI/buffers/carray:
    - carray indexing handles negative indices now according to usual vector
      convention.
    - New convenience functions for I/O between files/streams and buffers.
  - Build:
    - improved handling of test targets in Makefile
    - in condensed mode ("CC file.o" output) if the build step fails, the
      failed command is printed in detail.
  - Windows port:
    - Cygnal DLL updated to Cygwin 2.9.0 baseline from 2.5.2.
  - Vim:
    - % is correctly considered a symbol constituent.

  Bugs

  - partition, partition*, split and split* handle infinite lazy
    lists of indices; issues in their < TXR-171 compatibility
    have been addressed.
  - tprint function and -t command line option deal with lazy lists
    in constant memory now.
  - completely broken copy-hash fixed.
  - Awk macro: fixed hygiene problem in expansion.
  - carray: stability: missing type checks added in several functions.
  - open-command now accepts "b" mode flag even on POSIX platforms whose
    popen function rejects it with a failure.




                                    TXR 186
                                   2017-09-16


  Features

  - math:
    - new cum-inv-norm function for calculating inverse of
      the normal distribution.
    - new poly and rpoly functions for evaluation of single-variable
      polynomials, given coefficients and domain value.
  - macros:
    - new macroexpand-lisp1 and macroexpand-1-lisp1 functions
      for expanding forms in an assumed Lisp-1 style evaluation
      context.
  - regex:
    - new regex-prefix-match function
      - determines whether string is a prefix of a possible match,
        even if it is not itself a match.
    - optimizations implemented to reduce NFA graph size.
    - printed representation of regexes based on original
      source code, not AST-optimized version.
  - command line:
    - txr -i <file> now goes to REPL even if loading <file> throws
      exception.
  - listener:
    - Visual feedback is now given when Enter is pressed at
      the end of a line that is not accepted due to unbalanced syntax.

  Bugs

  - listener:
    - Enter pressed in Ctrl-X context now correctly leaves
      Ctrl-X context (in situations when line is incomplete
      and not submitted).
  - Lisp syntax:
    - precedence of range .. now lower than referencing dot,
      so a.b .. c.d parses in intuitive way.
  - regex:
    - fixed incorrect printing of | relative to catenation
      - e.g. #/abc(def|ghi)/ was printing as #/abcdef|ghi/
      - recent regression
  - syntactic places:
    - if form [m ...] is used as a place, m is now correctly
      macro-expanded in a Lisp-1 context.



                                    TXR 185
                                   2017-08-30


  Features

  - The op/do macro implementation has been rewritten
    in Lisp:
    - Substitution of the @1 notation to anonymous lambda
      argument terms now leverages local macros, so that
      it follows a correct code walk.
    - Will not get stuck in an infinite loop if quoted
      literals occur that contain circular structure.
  - Meta expressions like @foo and @(bar) can now be used
    in the dot position of a function call
    - Example:
      (macrolet ((sys:expr (x) ^(quote ,x)))
        (list . @(a b c)))
      -> (a b c)
    - related to the op rewrite, which relies on it
      to preserve the behavior of forms like (op fun . @1)
      previously implemented in op itself.

  Bugs

  - Fixed a five-and-half year old bug in replace-str,
    introduced between TXR 54 and 55. This affects other
    operations such as (append "str1" "str2").



                                    TXR 184
                                   2017-08-23


  Features

  - TXR ported to 64 bit ARM8 ("aarch64").
  - out-of-memory handling revised:
    - throws exception rather than aborting.
    - code for this was very old and long neglected.
  - lib:
    - set-diff is called diff now; old name deprecated
    - isec and uni functions provide intersection and union.
      - names harmonize with hash-diff, hash-isec and hash-uni
    - len synonym for length
    - spl and tok functions: variants on tok-str and split-str,
      with argument order more suitable for currying.
  - math:
    - new functions digpow and digits
      - (digpow 1234) -> (1000 200 30 4)
      - (digits 1234) -> (1 2 3 4)
      - other bases than ten via optional second arg.
    - new functions sum and prod for adding or multiplying
      sequence of numbers without having to apply or reduce
      through + or *.
    - new divides function for divisibility testing.
    - bit functions logand, logior and loxor allow character operands.
    - function bit can test bit of character
  - control flow:
    - new macros doloop and doloop*
    - trivial case of tagbody optimized away.
  - extraction language:
    - bi-directional string tree match semantics for non-variables
      in @(bind) and other contexts.
  - FFI:
    - new buf-carray-function
    - new functions for reading and writing FFI types from and to streams.
  - I/O streams:
    - New stream type for doing I/O from and to a buffer.
    - Functions for Base64 encoding and decoding from one stream to another.
    - length argument in truncate-stream function now optional
      - defaults to current read/write position
  - parser:
    - more efficient treatment of string literals.
  - improvements in Vim syntax coloring.

  Bugs:

  - listener:
    - recognizes incomplete buf literals properly as open syntax.
  - tagbody:
    - tagbody was setting up anonymous block, which it must not.
  - pad function
    - spurious instances of nil were occurring in its output.
  - n-ary math-functions:
    - were not checking the one-arg case, e.g. (+ "foo") -> "foo"
      which should be an error.
  - tok-str:
    - wrongly permitted a call with just one argument.
  - streams:
    - seek-stream was not working when :from-end specified.
  - buffers:
    - buf-put-uchar was broken.
  - parser:
    - fixed "yacc stack overflow" when compiled with Byacc.
    - fixed broken #; syntax handling when compiled with Byacc.
    - fixed broken handling of empty buffer literals.
  - buffers:
    - fixed infinite loop in buf_grow function.



                                    TXR 183
                                   2017-07-19


  Features

  - Extraction Language:
    - New :lists parameter in @(collect)/@(coll)
      - Specifies variables which are are ensured as bindings
        to lists, even if they match nothing, without the
        full blown discipline of :vars.
  - FFI:
    - carray-buf, ffi-get, ffi-put-into, and ffi-in get
      an offset parameter for added flexibility.
  - Environment:
    - The accessors symbol-function, symbol-value and symbol-macro
      can now create bindings that don't exist, when assigned,
      rather than throwing errors.
    - Storing to a (symbol-function (meth ...)) place can define
      a method now.
  - I/O:
    - The format function can now pad floating-point numbers with
      zeros, if a leading zero flag is specified on the precison.
    - remove-path: exception semantics adjusted.
    - New path-cat function for easy catenation of paths.
  - getopts:
    - New argument type :text for an option whose argument is
      a string that is treated as raw text, and not TXR Lisp
      literal syntax as with the :str type.
  - List/Sequence processing:
    - New function, relate: turns corresponding elements from
      a pair of sequences into a translation function.
    - New accessor nth, like ANSI Lisp nth.
    - find and pos functions optimized and improved in
      support of objects that implement sequences.
  - Filters:
    - New *filters* special variable exposed. This holds the
      named filters used in the extraction language, as a hash
      table.

  Bugs

  - Fixed spurious warnings occurring in some situations when
    functions are invoked using square bracket syntax.
  - Fixed runaway recursion when trace macro used
    to trace the * or format functions.
  - regex: regex printing no longer renders superfluous parentheses
    around character classes.
  - getopts: fixed broken custom option type.



                                    TXR 182
                                   2017-07-09


  Features

  - Lisp:
    - Lambda expressions are function names now, improving compatibility
      of TXR Lisp with other dialects.
  - FFI:
    - Support for preparing zero-filled objects for foreign functions:
      - New functions zstruct and zero-fill, and new macro znew.
    - Relaxation in cptr type allowing a nil-tagged cptr null pointer to
      convert to foreign pointer through a cptr FFI type bearing any tag.
  - OOP:
    - New functions provided for accessing and storing a struct type's
      initfun and postinitfun.
    - The keywords :init and :postinit can be used in the place of
      method names, allowing a struct type's initfun and postinitfun to be
      redefined using defmeth syntax, and also referenced using
      the (meth type slot) syntax.
  - Doc improvements:
    - FFI restructured into major section with better divisions.
    - Better HTML TOC: [+] [-] open/collapse UI rearranged.

  Bugs:

  - OOP:
    - bugfixes in static-slot-ensure also affecting defmethod.
  - Listener:
    - newlines occurring in material pasted with Ctrl-X P (result of previous
      evaluation) are properly treated now as line breaks.
  - build: configure script triest to detect deviant libffi installations,
    like that of Arch Linux.
  - call-super-method function deprecated.



                                    TXR 181
                                   2017-07-01


  Features

  - FFI:
    - new cptr functions cptr-cast and int-cptr.
    - new macro deffi-sym
    - enums can be based on types other than int.
    - make-union can specify an initial value, and optionally specify the
      member for that value (defaulting to the first member).

  - Lib:
    - New Cartesian product mapping functions: maprod and maprend.

  Bugs

  - FFI:
    - fixed broken "in" semantics of zarray types.
    - fixed failure to null terminate zarrays.
    - fixed broken struct/union returns on big endian.
    - fixed bool types reporting as integers in the
      printed #<ffi-type ...> notation.
    - fixed more bugs in bitfield layout leading to
      incorrect placement and retrieval of bitfield values.
    - fixed union types reporting as struct types
      in the #<ffi-type ...> notation.



                                    TXR 180
                                   2017-06-25


  Features

  - FFI:
    - new types: bool, longlong, ulonglong.
    - support for C unions.
    - improved support for type-tagged cptr.
    - some performance optimizations.

  Bugs

  - Fixed regression in horizontal @(trailer) introduced in 170.
  - Fixed broken append redirection operator ->> in awk macro.
  - FFI:
    - fixed broken float put operation.
    - fixed broken handling of cptr when parametrized by tag symbol.



                                    TXR 179
                                   2017-06-18


  Features

  - FFI:
    - carray-sub function becomes accessor.
    - New functions num-carray and unum-carray to treat
      carray as a binary blob holding an integer,
      which is extracted.
    - New functions carray-unum and carray-num, which
      convert the binary image of an integer into a carray.
    - New copy-carray function, hooked into copy function.
  - Listener:
    - Multi-line mode is now default.
    - New Ctrl-X ? displays "cheat sheet" of interactive commands.
    - Open syntax is now detected:
      - when Enter is pressed in incomplete expression, a line
        break is inserted.
  - Sequences:
    - Functions length and empty now check whether a structure has
      a method called length and use it.
    - New concept being introduced: sequence that are not vectors, strings or
      lists can be "vector-like" or "list-like".
      - A struct is a vector-like sequence if it has lambda and length
        methods.
    - reverse and nreverse handle generalized sequences:
      - can be applied to carray
    - ref and refset now work on structs, via lambda and lambda-set.
      - could be considered a bugfix.

  Bugs

  - Numerics:
    - Fixed sign-extend function, broken for bignums.
    - Hardened the MPI library:
      - Clamped the maximum digit size to prevent numeric overflows
        in bignum sizes and bit counts.
      - Introduced new MP_TOOBIG error into MPI library, which is
        is handled in TXR Lisp runtime.
      - bit count argument of ash function range checked,
        since it must fit into the C type int.
  - Fixed neglect to autload place macros.
  - FFI:
    - fixed bugs in bitfield layout.



                                    TXR 178
                                   2017-06-12


  Features

  - FFI:
    - carray objects greatly extended:
      - element selection with select
      - assignable indexing and range selection
      - integration with the [...] syntax, ref, refset, sub and replace.
      - carray-get and carray-put functions make carrays
        more convenient for handling C arrays across FFI.
      - length function supports carray.
      - carray-pun function lets carray be reinterpreted as
        an array of a different element type.
      - carrayp function for testing whether object is carray.
    - if libffi is missing at build configure time, much more functionality
      from the FFI module is now retained.
  - Buffers:
    - ref and refset indexing supported, along with [...] syntax.
    - bufp function.
  - Awk macro:
    - new fconv conversions c and cz for C notation 0x... hex, 0... octal.

  Bugs

  - Added missing overflow checks in memory allocation code in various
    places in library: FFI, streams, system interface.
  - Fixed bug in vector function, allowing the negative sizes -2 and -1
    to get through.
  - Awk macro:
    - fixed broken rng (basic both-endpoint-inclusive form)
  - FFI:
    - fixed failure to trigger string conversion for arrays whose
      element is a character typedef rather than direct character type.
    - fixed broken get semantics of incomplete (zarray char),
      and likewise for (zarray bchar) and (zarray wchar).
      - was getting a vector rather than string.



                                    TXR 177
                                   2017-06-07


  Features

  - FFI:
    - bitfields:
      - struct members may be bitfields, using 1, 2 or 4 byte storage cells.
    - enums:
      - enum types convert between sets of symbols denoting numeric values,
        and FFI type int.
    - align operator in type language:
      - the alignment of types can be customized to achieve effects like
        packed structures, or conformance with unusual alignment requirements.
    - endian types:
      - big and little endian versions of int16, uint16, ... int64, uint64,
        float and double.
      - FFI transparently handles conversion.
    - new macros: alignof, offsetof, arraysize, elemsize, elemtype
    - numeric values in type language such as array sizes are now
      evaluated expressions.
    - new val type for transparently passing raw Lisp values.
  - Streams:
    - New put-buf and fill-buf functions for I/O based on buf type.
      - FFI-type-driven conversions to/from buffers combine with buf I/O,
        allowing TXR to deal with binary data in files and over networks.
  - Command Line:
    - new *args-eff* variable provides access to transformed command
      line arguments.
    - "Hash bang" support rewritten, and now features a "hash bang null hack":
      - Additional arguments to TXR may be encoded in a hash bang line
        after a null byte.
  - lib:
    - mkstring's <char> argument now optional, defaulting to space.

  Bugs

  - FFI:
    - lingering broken assumption that alignment of pointers is the same
      as their size.
    - GC integrity issue in carray and cptr objects.
    - Another GC integrity issue affecting basic FFI types.
    - fixed incorrectly coded exception throws affecting code which
      misuses one of the four functions that connect FFI and buffers.
    - slots named nil in a FFI struct are now culled when making the
      corresponding Lisp struct type.
    - fixed broken handling of return values on big-endian platorms,
      related to a historic quirk in libffi.
    - fixed some broken conversions and range checks affecting some
      integer types.
    - fixed broken get semantics for arrays of bchar.
      - failure to null-terminate decoded string.
    - fixed clockid-t type not being defined on platforms that do have
      the corresponding clockid_t C type.
  - Build system:
    - "make tests" doesn't cache output of failed tests, so they are repeated
      when re-invoked.



                                    TXR 176
                                   2017-05-21


  Features

  FFI:
  - New tagged variant of cptr type, for improved safety.
  - New carray type for handling arrays of unknown size,
    where FFI's automatic memory handling isn't of help.
  - deffi-type is just called typedef
  - New ffi macro providing a shorthand for ffi-type-compile.
  - Variable length arrays that are null-terminated (zarray <type>)
    now have useful semantics: the type can extract an arbitrarily
    long null-terminated array from foreign memory.
  - Previously undocumented ffi-call function is now documented,
    and has undergone an API change.
  - deffi macro now generates Lisp functions with fixed number of
    arguments, so a mismatch in number of arguments is caught
    at the wrapper level, rather than down inside ffi-call.
  - New deffi-var macro for defining a Lisp variable connected
    to a foreign variable.
  Awk macro:
  - New (again) operator for repeating all the rules against
    the same record.
  Filesystem:
  - New functions dir-name, base-name and variable path-sep-chars.
  - New function realpath, wrapper for the POSIX one.

  Bugs

  - fixed corrupt line numbers being reported in some
    situations, like unbound variables inside quasi-word-list literals.
  - FFI:
    - fixed broken in semantics of buf type.
    - fixed broken alignment of basic types leading to wrong
      struct layouts.
    - nil value now handled by FFI buf type, mapped to null pointer.
    - A ffi call now releases up temporary local memory when an
      exception occurs in the argument preparation phase.
    - A ffi callback similarly releases any temporary memory
      allocated during the preparation of the return value, if
      the preparation terminates due to an exception.
    - Defense in the type system against incomplete (i.e. zero sized)
      types being passed or returned by value, or used as array
      elements or struct slots.
    - Fixed wrong documentation about variable-length arrays corresponding
      to pointers.
    - FFI calls are now checked for proper number of arguments.



                                    TXR 175
                                   2017-05-15


  Features

  - New: Foreign Function Interface (FFI)
    - Declare bindings to C-compatible functions in other software
      components (dynamic libraries).
    - Use Lisp functions as C-compatible from foreign software
      components.
  - New :prompt command in listener, nicknamed :p, which
    turns on prompts, useful in the plain mode listener.
  - stat structure has a path slot now, for convenience;
    - answers question: if the stat was obtained from a path,
      what was that path?
  - Built in functions and macros can now be redefined:
    only a warning occurs, rather than error.
  - New buffer data type.
  - Functions related to cptr type exposed.
  - Funtions dlopen, dlsym and related functions exposed.
  - OOP:
    - new and lnew macros now check nonexistence of base type at
      expansion time and generate immediate warning.

  Bugs

  - Printing issue with embdedded symbols in quasiliterals.
  - Fixed broken printing of quasi-word-list literals.
  - @{expr [index]} substitution syntax now indexes into
    any kind of sequence, not only lists.
  - Tightening in parser to reject certain unassigned syntax
    like #[], and better error checking over hash literals.
  - Bugfixes in area of processing TXR pattern language in context
    of user-defined package.
  - OOP print methods can now disable *print-circle* over
    recursive print calls.
  - Unintering built-in symbols is now possible without
    catastrophic results.
  - Fixed error in macro-expander's traversal of the special
    forms return-from, sys:abscond-from and block*.
  - Fixed bug in expander for suspend macro.
  - Fixed bug in the ash function when right shifting fixnum integers.
  - Fixed tostringp not behaving for float numbers in documented manner.
  - mkstring and vec-set-length defend against negative argument.
  - lognot and logtrunc defend against negative number of bits.
  - Fixed bug in --free-all logic when --vg-debug in effect.
  - Fixed incorrectly ordered logic in make-catenated-stream, exposing
    a Lisp object to premature reclamation.
    - Reproduced as actual issue on Darwin, under the --gc-debug
      GC torture test.



                                    TXR 174
                                   2017-04-04


  Features

  - TXR Pattern Language:
    - The special phrase forms like @(collect) and @(end) are now integrated
      with the package system.
  - opip macro:
      - forms like .a.b or .(meth x y) occurring in opip
        now evaluate to functional pipeline terms as expected.
  - Lexical syntax:
    - Dubious run-on lexical forms like 0.1.2 and .1.1 now diagnosed.
  - Time:
    - New functions time-parse-local and time-parse-utc.
  - Listener:
    - The -n option now has the additional effect of forcing the listener
      into plain input mode (no editing, history, or completion) even if
      the input device is a TTY.

  Bugs

  - Fixed broken support for building in separate directory.
  - Floating-point constant regression: .123 being misinterpreted as a slot
    access if preceded by whitespace.
  - Fixed rejection of 0.1..0.2 range syntax with floating-point operands.
  - Fixed a...b syntax error. This is a .. .b.
  - Fixed apply and iapply broken behavior: not splitting non-list
    sequences into individual arguments, like documentation says.
  - Linenoise issue fixed: when reading from a non-tty mode without
    editing, the continuous instantiation of a new buffere stream
    was causing input data to be discarded.
  - Scanner issue fixed: `@@1abc` was being interpreted as `@{@1}abc`
    rather than `@{@1abc}`.



                                    TXR 173
                                   2017-03-25


  Features

  - Listener:
    - Completion is now sensitive to slot or method context: .(abc[TAB] and
      .abc[TAB] searches appropriate spaces.
  - TXR Pattern Language
    - Unbound variable followed by directive is now bound to partial
      match result while searching for match for directive.
  - GC:
    - Finalizers may now invoke call-finalizers; behavior no longer unspecified.
  - Lisp code processing:
    - Warnings issued when expanding code that accesses nonexistent struct slots.
      - Not a form of type checking at all, but catches many typos.
  - Windows:
    - Improved 16x16 icon.

  Bugs

  - Lisp code processing:
    - Fixed missing warnings when main module is a .txr file.
    - Fixed missing unbound variable/function warnings for unbound symbols that
      are the direct operands of [...] syntax.
    - Fixed wrong name being printed in trace messages, when trace is used
      to simultaneously enable tracing for two or more functions.
  - Windows:
    - Start menu shortcut now starts in user profile dir, rather than
      incorrectly in TXR standard library installation dir.



                                    TXR 172
                                   2017-03-19


  Features

  - Argument of umask function is optional
    - if omitted, function returns current umask.
  - OOP:
    - new static-slot-home function
      - reports the base class which actually
        defines a slot.
  - Sandboxing support:
    - New *package-alist* variable gives application control
      over what packages exist over a dynamic scope.
      - Makes possible safe evaluation of TXR Lisp code obtained
        as input from untrusted source.
      - Special behavior worked into exception handling to
        close a potential sandbox hole.
  - Tracing:
    - trace now canonicalizes a method name to the
      base class which defines a method and produces
      a warning if this is different from what was requested.
      - E.g. (trace (meth dog speak)) is issued, but dog
        just inherits (meth animal speak) which is what is
        actually traced.
    - warnings issued when traced functions are redefined.
  - Windows:
    - New icons, redesigned from scratch.
    - SVG logo now in source tree.

  Bugs

  - Parser fix in relation to new unbound reference
    dot syntax: now it may be a top-level expression,
    so entering .a.b.c into the REPL isn't a syntax error.
  - Missing documentation for opt function added.
  - Windows:
    - Fixes from Cygnal:
      - dir and shell fields in password structure
        returned by getpwent are Windows paths that
        make sense.
      - HOME environment variable has same value as USERPROFILE.
      - Fixes issue when Windows Vim is invoked out of txr,
        of Vim being confused by nonsensical HOME value.
    - Linenoise fix: Ctrl-X Ctr-E (edit in external editor)
      - Now temp file closed before spawning external editor.
      - Fixes issue of editor reporting that the file is
        in use by another application and not being able to save.
      - Fixes issue that Vim reports the file as readonly.



                                    TXR 171
                                   2017-03-14


  Features

  - New unbound referencing dot syntax: .a.b.c.d
    corresponding to (uref a b c d) macro operator
    - Produces a function which curries slot references,
      binding them to an object passed to it as argument.
  - Command line:
    - The argument - (dash) is no longer required to specify
      that standard input is to be scanned; it is default behavior.
  - TXR access from Lisp:
    - last two arguments are now optional in match-fun.
  - OOP:
    - new functions struct-from-args and struct-from-plist
      provide slightly simplified interfaces to make-struct.
    - A structure's print method can now return : (the colon symbol)
      to indicate that it declines printing, so the built-in structure
      printing takes place.
      - suppresed by -C 170 (or lower) compat option.
  - Sequences library:
    - new rmismatch function: compares tails of sequences and
      reports mismatching position as a negative value.
    - new functions starts-with and ends-with.
    - split, split*, partition, partition*: now allow negative
      indices.
      - previous behavior of ignoring negative indices can be selected
        using -C 170 (or lower).
  - TXR Pattern Language:
    - New directive @(mdo): "macro-time do": evaluates Lisp code
      immediately after being parsed and disappears from syntax tree.
    - New @(in-package) directive, allows pattern language files to
      succinctly express being in an alternative package.

  Bugs

  - Fixed spurious warnings about :vars set up in @(repeat)
    being unbound as well as the :counter variable in @(collect).
  - Fixed lack of macro-expansion on the init expression
    in @(collect :counter (var init)).
  - The TXR matcher now refuses to open input sources that are
    streams, or standard input default, for non-matching directives,
    in the same manner that file name sources are treated.
    Thus @(next s) (where s is a stream) not cause any input
    to be pulles from s until a matching directive is encountered.
  - match-fun: @(next) in the invoked pattern function now correctly
    switches to the first file in the list of files passed
    to match-fun.
  - Fixed numerous instances of improperly terminated formatted
    printing in the TXR internals (missing "nao" argument).



                                    TXR 170
                                   2017-02-28


  Features

  - Horizontal-mode @(throw) directive.
  - Horizontal @(block)...@(end) syntax.
  - Second argument of trunc function is now optional:
    (trunc -1.5) yields -1.0.
  - floor and ceil functions take optional second argument,
    which acts as a divisor: (floor 10 3) -> 3; (ceil 10 3) -> 4.
  - New round function: (round 0.7) -> 1; (round 3 4) -> 1; (round 1 3) -> 0.
  - New functions floor-rem, ceil-rem and round-rem.

  Bugs

  - Requirements for special interaction between @(accept)
    and @(next), function calls, and @(finally) have been
    identified and implemented.
  - Fixed segfault (C null pointer dereference) when nil
    symbol used to look up a struct slot.



                                    TXR 169
                                   2017-02-11


  Features

  - Improvements in area of warnings and deferrable warnings.
    - Representation of deferrable warnings changes; the defr-warning exception
      type derived from warning is used.
  - Awk macro:
    - Now provides a warning when a rng expression appears to refer to a local
      variable or function that is unreachable due to the code relocation.
  - New functions rassoc and rassql.

  Bugs

  - compile-warning function: added missing catch in compile-warning
    functionfor continuing after warning is handled.



                                    TXR 168
                                   2017-02-05


  Features

  - Mutation of lexical functions is forbidden and diagnosed.
    - e.g. (set (fun f) ...) when f is lexical.
  - Improved diagnostics during place expansion and when
    exceptions occur at macro-expansion time.
  - New function rlcp-tree.
  - New macro whena, complements ifa and conda.
  - Functions remq, remql, remqual, remove-if, keepq,
    keepql, keepqual and keep-if were rewritten and work
    more efficiently for vectors and strings.


  Bugs

  - Fixed an issue in the the expansion of Lisp-1 forms as places.
  - Fixed ocurrence of "expansion at nil" diagnostic in some
    error traces.
  - Fixed printing of unnecessary package prefix on symbols which
    are visible in the current package, but not interned in it.
  - Fixed rehome-sym not removing symbol from hidden list of
    destination package, as documetned.
  - Fixed broken keepql function.
  - Fixed bug in poll function: rejecting stdio-stream type
    objects as non-streams due to strict type check rather
    than subtype.



                                    TXR 167
                                   2017-02-02


  Features

  - New functions defer-warning and dump-deferred-warnings.
  - Awk macro:
    - small convenience: an input source given in :inputs can now be a list of
      strings, which the macro converts to a stream.
  - Tightening in syntax:
    - When floating-point tokens are followed by a period and a non-period
      character, this is now a "trailing junk" syntax error:
        SYNTAX         OLD BEHAVIOR             NEW BEHAVIOR
        1.$            "trailing junk" error    "trailing junk" error
        1.0.$          (qref 1.0 $)             "trailing junk" error
        1.0.a          (qref 1.0 a)             "trailing junk" error
        1.0.0          1.0 0.0                  "trailing junk" error
        1.1.<EOF>      generic syntax error     "trailing junk" error
    - Spliced symbols are diagnosed as "bad token" syntax errors
        SYNTAX         OLD BEHAVIOR             NEW BEHAVIOR
        :a:a           :a :a                    "bad token"
        @a@a           @a @a                    "bad token"
        usr:foo:bar    usr:foo :bar             "bad token"
   - These changes are not subject to -C option: code must be fixed
     if it contains these incorrect lexical forms.

  Bugs

  - The sort function now actually implements a stable sort over lists,
    as has been documented for a long time.
  - Missing autoload registrations for catch* and handle* added.
  - Parameter list macros now recognized in the parameter list of a catch
    clause.
  - Fixed incorrect printing of a symbol that is not visible in the current
    package due to being hidden by a like-named symbol: such as symbol must be
    printed with its package qualifier.
  - Fixed issue: Lisp files loaded from the command line were showing spurious
    undefined warnings that wouldn't appear if the same files were loaded with
    (load ...).



                                    TXR 166
                                   2017-01-26


  Features

  - Deferred warnings
    - System of deferred warnings implemented allowing forward references
      to functions, variables and anything else (extensible).
  - New error reporting convenience functions for macro writing: compile-error,
    compile-warning, compile-defr-warning.
  - A parameter list macro called :key is provided, allowing functions
    and macros to easily take keyword parameters.
  - New memp function for searching a property list.
  - New functions plist-to-alist and improper-plist-to-alist.
  - New macros catch* and handle* which provide catches and handlers access
    to the exception symbol.
  - Local macrolets established by the build macro such as add, pend,
    pend* and others are now functions.
  - Awk macro:
    - *stdin* now bound to current input stream.
    - new fname variable analogous to FILENAME.

  Bugs

  - Unbound functions diagnosed consistently between
    dotted (fun ... . x) forms and ordinary.
  - *stderr* bound on entry into the repl, so errors sent to *stderr* go
    to the repl's output stream.
  - Better error reporting for nonexistent base in defmeth.
  - Fixed broken supertype check in make-struct-type also affecting
    defstruct, a nonexistent base to be treated as if it were nil.
  - Fixed compound forms not being expanded in quasiliterals. This is a
    TXR 160 regression breaking `@(macro ...)` usage.
  - Muffle expansion-time warnings in op macro expander.
  - Fixed missing macro expansion of TXR Lisp forms in collect, coll, gather,
    output, and numerous other TXR directives.
  - doc: missing documentation for :var argument of @(next) written.
  - Fixed small ambguity issue in expansion of keyword args in
    @(repeat)/@(rep).
  - Fixed an expansion issue affecting output vars.
  - *package* subject to rebinding in @(load) just like in the Lisp
    load function.
  - Cleaned up sloppy expansion in braced variables.
    The argument of the :filter keyword isn't expanded.
  - Fixed poor expansion order of parameter list macros, and a related bug.
  - Fixed :whole and :form arguments in macro parameters lists not allowing
    destructuring (due to an exception being thrown at expansion time
    if their arguments are not bindable symbols).
  - Fixed init-forms of optional arguments being expanded in an
    incorrect macro environment, in which earlier arguments are not
    visible as they should be.
  - Fixed broken termination tests in take-while and take-until.
  - Fixed wrong form being taken as the to-be-destructured form in
    mac-param-bind.



                                    TXR 165
                                   2017-01-10


  Features

  - New Lisp concept: parameter list expander macros.
    - customize function behavior with attribute-like keywords which invoke
      custom expanders to transform bodies and parameter lists.
  - Throughout the TXR pattern language parser, checks against empty clauses
    have been eliminated. Empty clauses in numerous situations are not
    considered syntax errors.
  - The last variable in whilet can be omitted in the same way like in iflet
    and whenlet.

  Bugs

  - Fixed missing space between attribute keywords in the printed
    representation of a hash.
  - Windows native version picks up fix for Cygnal issue 15.



                                    TXR 164
                                   2017-01-01


  Features

  - Awk macro: new variable fw for delimiting records according to fixed field
    widths.
  - The last variable may now be omitted in the bindings list of iflet, whenlet
    and condlet, leaving just the controlling expression, not bound to a
    variable.
  - Various syntax checks over function and macro parameter lists, and variable
    bindings, have been moved out of run time and into expansion time.

  Bugs

  - Build: "make clean" now removes txr-win.exe
  - Fixed a lingering bug in the handling of special variables in parallel
    binding, not fixed in the work done in this area for the previous release.
  - Fixed a bug in the handling of optional-argument presence indicating
    arguments: not binding them dynamically when they are special variables.
  - Fixed inconsistency in the regex-source function: the source of the
    (compound "str") regex was reported as "str", which isn't the same thing
    when fed to the compiler.
  - Fixed completely broken quasi-quoting over #R range literal syntax.
  - Fixed a read/print consistency problem in quasiliterals.
  - Fixed a problem with catch operator form not being fixed-point stable
    under repeated passes through the expander. To fix the problem, catch
    has turned into a macro which expands to an internal sys:catch operator.



                                    TXR 163
                                   2016-12-20


  Features

  - New equot macro: quote after macro expansion.
  - CL compatibility:
    - New function endp.
    - New function mismatch.
    - New prog and prog* macros.
  - Signal handling:
    - If an async signal is caught and handled by Lisp code during gc, gc is
      canceled.
      - Allows recovery from segfault due to stack overflow during gc.
  - Exception handling:
    - New function find frames.
  - Awk macro:
    - New awk local macros -rng, rng- and -rng-, providing endpoint-exclusive
      variants of rng.
  - Redesigned binding of special variables.
    - Fixes subtle bugs
    - Reduces number of variable binding special forms.
    - Removes special var handling responsibility from binding special forms.

  Bugs

  - Method lookup doesn't throw on nonexistent slots.
  - Fixed find-max not handling interpreter literal strings.
  - Expansion bugfix in tagbody.



                                    TXR 162
                                   2016-12-07


  Features

  - Awk:
    - Awk prn macro is now a function: can be used as a functional argument

  - Regex:
    - New functions fr^$, fr^, fr$ and frr.


  Bugs

  - Awk:
    - fixed assignment to field list f not yielding the new value as a result,
      returning another object instead.
    - input processing loop containing no cond-action clauses was being elided,
      even if it contained :begin, :end, :beginfile or :endfile clauses which
      must be executed.
    - awk macro implicitly obtaining its input sources from the command line
      wasn't consuming the command line, causing problems when macro is used
      from the command line.
  - Syntax, input:
    - Fixed robustness issue in handling of out-of-range hex/octal character
      escapes.
      - This fixes a crash that could be triggered in the regex module by
        a regex containing out-of-range character escapes in a character class.
    - Stray debug printf removed from lexical analyzer.
      - Occurred only when diagnosing certain invalid floating-point syntax.
    - Fixed syntax error being reported when last item in a Lisp source
      file or :read paste in the REPL is an object erased with #; notation.
  - Syntax, output:
    - Fixed ^(a . ,b) being printed as ^(a sys:unquote b).
    - Fixed ^(,* a) and ^(, *a) both printing as ^(,*a).
  - Exceptions:
    - fixed handle macro's deviation from documented syntax.
      - subject to compat option.



                                    TXR 161
                                   2016-11-28


  Bugs

  - Regression: awk macro spews warnings.



                                    TXR 160
                                   2016-11-27


  Features

  - New hash table function clearhash.
  - TXR Lisp macro-expanding code walker now generates warnings
    about unbound variables and functions.
    - ignwarn macro provided for ignoring warnings.
  - macro-time macro now interleaves expansion and evaluation, so that the
    evaluation effects of forms occurring earlier in the
    macro-time form are visible to the macro-expansion-time of later forms.
  - New exception-subtype-map function for retrieving type symbol hiearchy.

  Bugs

  - Fixed numerous bugs in macro expander:
    - not including symbols in macro-time environment:
      - macrolet arguments
      - dohash key and value variables
      - function name in defun
      - the auxiliary Boolean parameters that can exist on optional parameters
        which indicate whether the optional argument is present.
    - not expanding:
      - mac-param-bind special forms at all.
    - wrongly traversing and expanding:
      - @var and @(expr) syntax
    - incorrectly expanding:
      - arguments of op using Lisp-2 expansion style rather than Lisp-1.
  - Fixed a number of library functions broken due to using nonexistent
    variables: test-inc macro, str-inaddr-net, str-inaddr6-net,
  - Fixed broken read-print consistency of quasiliterals.
    - example: `@@@a` would print as `@@a` which is a different object.
  - Fixed op and related macros not handling @rest in the dot position.
  - Fixed interaction between circular notation and hash literals.
    - literals denoting eql-based hash tables which contain themselves
      as keys now work.
    - literals denoting equal-based hash tables doing the same thing
      are not supported for now; they produce junk hash tables.
  - Build system:
    - Changes in 159 caused builds to fail on some systems unless lex
      was manually specified.
      - On some systems the $(LEX) make variable points to something
        which isn't GNU Flex compatible.
      - On some systems $(LEX) points to a nonexistent lex even if
        Flex is installed.



                                    TXR 159
                                   2016-11-21


  Features

  - Tweaks in generational GC.
  - Rounding out of package system with "fallback" concept.
  - TXR Lisp now has a tagbody macro.
  - Macro bindings now hold first-class functions.
  - Global macros have (macro <sym>) function names
    - symbol-function works with (macro <sym>).
    - Possible to (trace (macro <sym>)) to trace a macro.
    - Posible to (defun (macro <sym>) args body ...) to
      write a raw macro expander as a plain function.
    - func-get-name applied to global macro expander function
      calculates its (macro <sym>) name.
  - Trace macro now throws error if an undefined function occurs
    in the argument list.
  - The previously deprecated -b option has been revived and repurposed:
    - use "-b sym=obj" syntax to pre-define a Lisp variable.
  - Build system:
    - TXR now honors standard Make variables like CC and CFLAGS.

  Bugs

  - Fixed macro-expansion bug in which forms are expanded
    at macro time, to determine whether or not they are constant,
    wrongly using the global macro environment rather than
    the lexical one.



                                    TXR 158
                                   2016-11-15


  Features

  - OOP:
    - New feature: dirty flag bit on struct instances. Code can tell if any
      instance slots were modified since last time dirty flag was cleared.
  - Packages:
    - New in-package macro.

  Bugs

  - Interactive txr switches *package* to user package before entering
    the listener, in case the specified script file alters it.
  - Fixed broken bignum addition.
  - Fixed breakage in fixnum to bignum conversion affecting 64 bit targets.
  - Fixed invalid mutation of applied argument list, affecting
    some functions. Test case: [apply lcm (list 1)] mutates (1) to (nil).



                                    TXR 157
                                   2016-11-14


  Features

  - New #; syntax for commenting out Lisp object.
  - #: syntax for uninterned symbols now works as an input notation.
  - Packages:
    - Overhauled implementation with increased scope.
    - New *package* special variable holds current package.
    - New concepts in package system: foreign symbols, hidden symbols.
    - New functions: package-local-symbols, package-foreign-symbols, use-sym,
      unuse-sym, use-package, unuse-package, unintern.
    - New defpackage macro.
  - Improvements in Vim syntax coloring; don't forget to install new txr.vim
    and tl.vim files.
  - New convenience functions for file or process I/O in one call: file-get,
    file-put, file-append, file-get-string, file-put-string,
    file-append-string, file-get-lines, file-put-lines, file-append-lines,
    command-get, command-put, command-get-string, command-put-string,
    command-get-lines, and command-put-lines.

  Bugs

  - Fixed an infinite loop in the processing of syntactic places: regression
    introduced in 156.
  - Fixed bug in processing of nested syntactic places like [place arg] where
    the inner place is a macro.
  - Fixed regression in awk macro introduced in 156, related to the above bug:
    not being able to assign to a field as in (set [f 3] "foo"). The bug was
    there before, but the change suddenly removed the accidental circumstances
    which protected the awk macro from reproducing the problem.
  - Fixed some additional problems in circle printing, in the printing
    of package objects and and interpreted functions.
  - A few GC-unsafe mutations were found in the TXR kernel, by inspection, and
    fixed. No actual instability was reproduced.
  - Fixed a bug in the caseq, caseql and casequal macros: single-atom key
    values were being exposed to evaluation rather than taken as themselves.
    This behavior can still be obtained with the compatibility switch;
    but it is recommended to first see whether switching to one of the new
    case constructs caseq*, caseql* or casequal* is feasible.



                                    TXR 156
                                   2016-11-05


  Features

  - time-parse function defaults to epoch time.
  - new accessors nthlast and butlastn.
  - sub function is now an accessor.
  - last and butlast functions are accessors, and get optional index argument.
  - Awk macro:
    - now supports pipe/file redirection.
  - Function tracing support: trace, untrace macros, *trace-output* stream.
  - symbol-function accessor can refer to methods via (meth ...) syntax.
  - restrictions in dwim places relaxed:
    in (set [x y] z), x doesn't necessarily have to be a place.
  - OOP:
    - new lambda-set method can treat [obj ...] expressions as places when obj
      is a struct.
    - new slots function for getting complete list of slots of a struct type.
  - New neq, neql and nequal functions for negated equality tests: for all
    those times you hate writing (not (equal a b)).
  - New command-line argument processing library.
  - Improved printing of error location, and tracing locations across place
    expansions.

  Bugs

  - quasiquote now works properly over struct literals.
  - wrong return value of nthcdr place fixed.
  - fixed circular printer blocking unwinding.
  - tok-str semantics adjusted once again to eliminate
    spurious empty tokens in some situations.
  - fixed broken tok-where (regression).
  - fixed potential incorrect evaluation order in dwim places.
  - fixed bugs in circular printing that traverses hash tables and objects with
    print methods
  - *stdout* now flushed when processing unhandled exceptions, so that
    diagnostics sent to *stderr* appear properly ordered w.r.t. prior
    *stdout* output.



                                    TXR 155
                                   2016-10-21


  Features

  - Common-Lisp-style circle notation supported now both on input and output.
    - *print-circle* special variable now exists.
    - supported across print methods.
  - OOP:
    - print methods now take three arguments rather than two, and are called
      for readable and pretty printing, not only pretty printing.
  - env-fbind and env-vbind functions allow nil env argument to denote toplevel
    bindings; thus they can be used to bind global variables.

  Bugs

  - fixed regression: inability to work with places denoted by compounded
    referencing dot; e.g.  (set a.b.c val)
  - fixed showstopper regression: inheritance of static slots causes assertion
    and crash at garbage collection time (while simply checking for a condition
    that is harmless in and of itself).
  - reduce-left: initial value pulled from the input list itself was not passed
    through key function.
  - fixed some places where a volatile qualifier on a local variable was
    missing, found by inspection: actual impact not determined.
  - Listener was sending error traces to *stderr* stream instead of the
    listener's configured output stream; that was causing confusing output
    sometimes.




                                    TXR 154
                                   2016-10-15


  Features

  - OOP:
    - Functions method and umethodk, and the macros meth and umeth,
      now take additional arguments which are curried into the method call.
  - Regex:
    - In the regex abstract syntax, the and and or operators are now
      n-ary, rather than being strictly binary.
    - New regex-from-trie function.
  - Listener:
    - New Ctrl-X Ctrl-P feature to paste the result of the previous
      evaluation into the current command line.
  - Time:
    - time struct supports gmtoff and zone fields, on systems where these
      are available in the C struct tm.
  - Hash tables:
    - the hash user data is now included in the printed notation for hash
      tables; thus, hash literals can specify user data.
    - new hash construction keyword :userdata supported alongside :equal-based
      and others, so hashes can be constructed with user data in various
      situations.
    - New function hash-userdata is an accessor (serves as a place);
      get-hash-userdata is deprecated.
   - Sockets:
     - address structures (sockaddr, sockaddr-in, sockaddr-in6, sockaddr-unix)
       now all have a family slot, so programs don't have to switch on
       the object type to map to a numeric address family.

  Bugs

  - Bugfix in argument handling affecting struct method calls.
  - Listener:
    - Fixed bug in Ctrl-X Enter (submit historic line and stay in history).
      - If the line being submitted is a duplicate, it would not submit
        the line, and the position in history wouldn't advance to the next.
  - OOP:
    - Fixed various situations in which abstract sequence objects
      (object supporting car, cdr and nullify methods) didn't work as expected.
      - for instance: length, sub and where functions.



                                    TXR 153
                                   2016-10-07


  Bugs

  - GC-related regression in static-slot-ensure fixed,
    affecting code which uses defmeth also, causing
    instability.
  - Fixed long-time GC-related issues in replace-struct
    and clear-struct which threaten stability.
  - Check for self-assignment in replace-struct.



                                    TXR 152
                                   2016-10-04

  Features

  - Licensing:
    - All license headers in source files reverted to BSD 2-Clause,
      not just the LICENSE file.
  - OOP:
    - Inheritance model for static slots has been revised.
      This is also a bugfix.
  - Range objects support a degree of arithmetic, and can be
    queried with zerop, length and empty.
  - Regexes:
    - Improvements in search-regex function and functions
      based on it: support for negative indices and more.
    - New rr function: regex search which returns a range,
      like range-regex, but better interface for currying.
    - New rra function: return all regex matches as range
      objects.
  - Awk macro:
    - New convenience clauses :set and :set-file,
      to reduce the verbosity of (:begin (set fs ":" ofs ":")).
      to just (:set fs ":" ofs ":").

  Bugs

  - Interactive listener:
    - VT100 arrow key can be issued after Ctrl-X extended mode prefix:
      cancels the Ctrl-X and is carried out.
  - OOP:
    - New static slot inheritance model fixes issues like
      method redefinition with (defmeth ...) inappropriately
      clobbering overridden derived methods differing from the
      original method being redefined.



                                    TXR 151
                                   2016-09-27


  Features

  - Licensing:
    - TXR returns to unmodified BSD 2-Clause
  - Better code generation for simple cases of place mutation.
  - Regex facelift:
    - regex objects are callable like functions.
    - Support for negative start or end positions in regex matching
      operations.
    - regsub function takes functional argument for more flexibility.
    - Numerous new convenience regex functions: m^, m$, m^$, r^, r$,
      r^$, f^, f$ and f^$.
      - these simulate full matching and anchoring in various situations.
    - New regex-source function, for obtaining a regex's original AST.
  - Awk macro:
    - conditions in cond-action clauses and in (rng start-cond end-cond)
      expressions can be functions or regular expressions, which are
      invoked on the record.
    - New fconv conversions: iz, rz and others which yield a zero value
      for empty, nonexistent or junk fields.
    - orec variable provides access to original record, useful when rec
      has been modified.
    - rs variable can be dynamically changed now, taking effect for the
      next record.
    - paragraph mode implemented based on POSIX description and
      observations of GNU Awk behavior.
  - Library:
    - New functions tointz and tofloatz.
    - New build macro for procedural list building.
    - New *load-path* special variable replaces the self-load-path
      symbol macro (which still exists but simply expands to
      *load-path*).
    - load is now a function rather than macro.
    - @(load)/@(include) directives now pull parent path from
      *load-path* variable, rather than own source location.
    - loading uses stricter criteria for deciding what relative paths
      are automatically resolved relative to *load-path*.
  - Streams:
    - New strlist input streams: treat a list of strings as multi-line
      text stream.

  Bugs

  - Awk macro:
    - fixed broken updating assignments to awk variables, such as
      (push item f).
    - awk now exits if there are no cond-action clauses.
  - Regex:
    - match-regex function now returns match length as documented.
    - Broken return value of match-regst fixed.
    - Type of a regex object is now regex, rather than sys:regex.
    - Exception in pretty-printing a correct expression, due to bug in
      handling the & operator.
  - Lists:
    - out-of-range negative indices over lists now yield nil rather than
      the first item.
  - Command line:
    - -Dvar=val binding are now visible to Lisp files.



                                    TXR 150
                                   2016-09-18


  Features

  - Awk macro:
    - New ft variable to optionally specify field tokenization
      as alternative to field separation via fs.
    - New kfs variable to arrange for field separators to be
      retained and represented as fields.
    - New krs variable to keep record separator matched by rs
      as part of record.
    - New fconv operator for succinct and flexible
      conversion of awk fields.
    - Don't rebind *output* if :output clause not specified.
  - New place-mutating macro: upd.
  - New keepq, keepql and keepqual functions.
  - Functions remq, remql and remqual take key argument.
  - split-str take boolean arg to keep separators, like tok-str.

  Bugs

  - Fixed incorrect behavior of functionsremq, remql, remqual, remove_if,
    and keep_if on strings.
  - Fixed broken regex complement operator.
  - Fixed broken while* and until* macro expanders.
  - Fixed bugs in split-str and tok-str.
  - Windows:
    - TXR's standard input, output and error will now be text
      streams, CR-LF externally.
      - This comes from a fix in the Cygnal library being picked up
        into the installer package.
    - Interactive mode uses USERPROFILE env variable for
      location of home directory for edit-in-editor feature.



                                    TXR 149
                                   2016-09-12


  Features

  - Implementation of Awk paradigm in Lisp syntax, in the form of awk macro.
    - TXR programs can now integrate the strategies used in Awk
      as part of their logic.
    - Awk one-liners from the command line possible.
  - New place-mutating operators:
    - pinc and pdec provide post-increment and post-decrement.
    - test-set, test-clear and compare-swap provide a conditional update of a
      place with useful return value.
    - test-inc and test-dec provide increment combined with a test
      of the value.
  - New slet and alet macros
    - companions to rlet, providing more aggressive ways
      than rlet for eliminating unnecessary temporary variables
      in macro expansions.
  - Change in trim-str function: what it considers whitespace.
  - Doc improvements:
    - Formatting problems.
    - Table of contents display issue under Chrome web browser.
    - meta-keywords now italicized in nroff man page output,
      allowing them to be colorized via customizing the less pager.

  Bugs

  - Fixed regression: @(rep) wrongly complains about an empty
    clause when it's not in fact empty.
    - Workaround: use @(coll) or add parameters inside @(rep).
  - Fixed bug in nthcdr defplace: not obtaining macro environment
    in valid way, breaking the test whether the list argument
    is a place.
  - Fixed symbol macros not being expanded in the X position
    of (set [X i] Y) and related situations.
  - Fixed semantic issue in the expansion of place macros.
    - Place macro calls are put only through at most one round of
      regular macro-expansion before being tested again for
      place macro expansion.
    - This allows macros to produce place macro calls.
  - Changed order of calls to :postinit handlers in struct
    instantiation: base first, then derived.




                                    TXR 148
                                   2016-09-01


  Features

  - time-parse function
  - time-string and time-parse methods on time struct
  - optimization added to quasiquote expander to generate better code.

  Bugs

  - Broken defvarl and defparml marking variables special, thus behaving like
    defvar and defparm, respectively.
  - Put limit on numeric range of @<num> arguments in op/do syntax, because
    this generates huge formal parameter
    lists. Found by AFL(fast) fuzzing tool.
  - Fixed generation of huge lists by trivial cases of nested quasiquote
    like ^^^^^^^^^^x. Found by AFL(fast) fuzzing tool.
  - Fixed runaway recursion that can occur in lazy struct initialization when
    cycles are present.
  - Fixed broken Lisp macro expansion in @(if) and output-side
    @(repeat) directives.
  - Rewrote poor, incorrect documentation of @(merge) directive.



                                    TXR 147
                                   2016-08-12


  Features

  - 64 bit Windows/Cygwin port.

  Bugs

  - Fixed native Windows TXR trying to use HOME environment
    variable when run from Cygwin.



                                    TXR 146
                                   2016-07-20


  Features

  - Time and space optimizations in execution of NFA regexes.
  - POSIX uname function exposed.
  - Print syntax which looks like their read syntax implemented for
    quasistrings and quasi-word-list literals.
  - Windows version ships with Cygnal 2.5.1.99 for better
    windows native support.

  Bugs

  - Text streams are not open with stdio "t" mode on Cygwin.
    This was a mistaken change present in 144 and 145.



                                    TXR 145
                                   2016-07-03


  Features

  - The Windows installer version of TXR is now packaged
    with the Cygnal DLL, which is the result of a new project:
    http://www.kyheku.com/cygnal.

  Bugs

  - Fixed crash in getaddrinfo when host is not found.
  - Issues in Windows version fixed by Cygnal project:
    - Fixed unwanted console window suddenly popping up when the
      console-less txr-win spawns a process.
    - Command spawning (sh function, open-command) doesn't require
      sh.exe shim executable any longer to switch to cmd.exe.
    - Fixed issue of messed up REPL display in multi-line mode,
      when lines reach the right edge of the display.




                                    TXR 144
                                   2016-06-29


  Features

  - TXR bids adieu to MinGW: the MinGW-based port to Windows is dropped.
    - Now that Cygwin is under the LGPL, the installer-based TXR
      for Windows is based on the Cygwin version of TXR, and includes
      all the required DLL's.
    - The benefits are great: the Cygwin port of TXR is much less crippled,
      thanks to the excellent POSIX support in Cygwin.
    - The interactive listener now works!
  - Improvements in the support for treating structs as sequences.
  - New --free-all command line option to get TXR to free all malloced memory
    before exiting.
  - Improved semantics of makunbound function: more similar to Common Lisp.
  - @(collect)/@(coll) take a :counter parameter now, with an optional starting
    value, for more streamlined enumeration of collected values.
  - Most TXR-style expression evaluation in the pattern language replaced
    by Lisp evaluation, reducing the need for @ noise.
  - Improved Valgrind support in garbage collector: Valgrind backtraces
    can be printed for interesting objects.


  Bugs:

  - Regression fix: @(catch) and @(finally) clauses can be empty once again.
  - Various memory leaks fixed: in handling of bignums, in syslog streams,
    dgram sockets and in the Lisp parser object.
  - Fixed out of bounds memory access in bit function.
  - Fixed broken (del (symbol-value 'sym)).
  - defsymacro removes existing special marking from symbol.
  - Fixed potential crash caused by bogus stray code in the GC marking
    function for syslog streams.
  - Fixed possible object leak in GC by managing free list in more
    disciplined way.



                                    TXR 143
                                   2016-06-04


  Features

  - Structs:
    - Structures can now support custom pretty-printing
      via a print method.
    - car, cdr, nullify, and from-list methods on structures allow
      them to behave as if they were sequences.
  - TXR Pattern language:
    - The "!command" and "$dir" convention for opening command pipe
      and directory steams has been removed: this will not be
      recognized on the command line or the @(next) or @(output)
      directives.
    - The "-" convention for denoting standard input is now
      only available from the command line, not from the @(next)
      or @(output) directives.
    - @(output) now evaluates the destination as a Lisp expression;
      no need to use the @ escape.
    - @(repeat) sees variables in more places:
      - In the output variable syntax @{a b [c..d]}, if b, c and d are
        variables, they are recognized by the directive and treated
        accordingly.
      - Previously @(repeat) would know about a, but have to be informed about
        the others via :vars (b c d).



                                    TXR 142
                                   2016-05-29


  Features

  - The remove-path funtion takes additional Boolean argument
    to suppress exception.
  - Better reporting of expansion locations across expansions
    of the op, do and related macros.
  - Support for deploying stand-alone executables.
  - Optimizations in hashing.
  - Support for byte-oriented stream operation instead of
    UTF-8 decoding.

  Bugs

  - Bugfix in clumped option processing: test case -B-c.
  - Uses of POSIX sleep function were removed. These occurred
    in tail streams implementation. This function can interact
    with the SIGALRM signal.
  - Fixed broken argument defaulting in take-until function.
  - Fixed regression from TXR 42 (!) in pattern
    function argument passing. This bug has evaded detection for
    100 public releases, over 4.5 years.
  - Added support for adherence to ISO C rules regarding switching
    between input and output operations on update streams,
    hiding this issue from TXR programs.  This seems to be needed
    on all tested platforms other than the GNU C library.



                                    TXR 141
                                   2016-05-20


  Features

  - Support for Unix terminal handling (termios).
  - New functions at-exit-call and at-exit-do-not-call, for registering
    actions to take when process exits.
  - New self-load-path symbol macro, allowing code to interpolate its load
    location.
  - Interactive listener now supports two behavioral styles of visual
    selection, controlled by new *listener-sel-inclusive-p* variable.

  Bugs

  - Incorrect argument defaulting in record-adapter function.
  - Incorrect argument handling in - and / functions,
    triggering error in [[flipargs -] 2 1]
  - Fixed gc-related bug in structs.
  - Fixed gc-related bug in recent cons recycling
    optimization.



                                    TXR 140
                                   2016-05-08


  Features

  - New fixnum-min and fixnum-max variables.
  - Improvements in pseudo-random number generator.
  - TXR extraction language:
    - New @(call fun ...) directive provides indirection on pattern
      functions, via symbols.
  - Unix security:
    - added setgroups, getresuid, getresgid, setresuid and
      setresgid where available.
    - added the setgroups function, where available.
    - added support for setgid operation.
    - New --rexec option to help with setuid on some platforms.
  - Process execution:
    - The standard input, output and error descriptors of subprocesses
      are now derived from the current *stdin*, *stdout* and *stderr*
      streams, making useful redirection tricks possible.
  - TXR now correctly calculates its sysroot even if the executable
    is renamed (within the same directory).
  - New filesystem access testing functions:
    path-readable-to-me-p, path-read-writable-to-me-p,
    path-strictly-private-to-me-p.

  Bugs

  - Serious bug fixed in bignum integers: incorrect treatment
    of negative values at the boundary between fixnum and bignum.
  - Fixed issue of TXR binary requiring an executable stack on
    GNU/Linux platforms.
  - Fixed broken setuid privilege dropping.
  - Bugfix in path-writable-to-me function.
  - Fixes in Vim syntax highlighting definition.
  - self-path, *args* and *args-full* now have bindings in
    the listener.



                                    TXR 139
                                   2016-04-23


  Features

  - Change of rules regarding Lisp variable visibility in TXR
    Pattern language.
  - unget-char now allows more than one character of pushback.
  - The POSIX fnmatch function is now available.
  - Rules used by object printer for deciding which character objects
    and string constituent characters to print using hex escapes
    have been harmonized together, with some changes to both.
  - path-private-to-me function avoids making unnecessary call
    to getgrgid, which is somewhat heavy-weight.
  - A list can now be passed as the path argument to the ftw
    function; it will recurse over it.

  Bugs

  - Issue of certain macros not expanding in @(output) blocks.
  - Macro not expanding as argument of @(if) directive.
  - Newline not being allowed in string fed to regex-parse.
  - Broken unget-char operation over string input streams.
  - Rewrite of horribly broken read-until-match function,
    which also fixes broken record streams feature
    (record-adapter function).
  - Fixed optional argument in get-string not defaulting
    properly.
  - Out of range character escapes are diagnosed better.
  - regex-parse was silently returning nil upon syntax
    errors; now throws exception.
  - regex-parse was not handling non-UTF-8 bytes in the
    string: are now mapped to U+DCXX block now and
    incorporated as literal characters.
  - Numerous memory leaks fixed which could occur in various
    functions if a type mismatch exception occurs after
    some local resource has already been allocated.



                                    TXR 138
                                   2016-04-16


  Features

  - New accessor sock-set-peer, and sock-peer becomes
    an accessor so (set (sock-peer sock) addr) is possible.
    - Allows "soft connected" datagram sockets:
      - send to different destinations with same socket
        by altering sock-peer address.
  - Dot position in function calls is now defined in terms
    of transformation to apply:
    - dot position expr can now be a symbol macro.
    - value of dot position is no longer applied as
      a list of arguments if it is a non-list sequence.
  - Better tracking of form expansion origins, leading to
    improvement in error diagnostics.
  - New fmt function for terse formatting to a string,
    shorthand for (format nil ...).
  - New open-socket-pair function, providing access to socketpair.
  - proper-listp function now known as proper-list-p.
    - old name still there, but deprecated.
  - New obtain* and obtain*-block macros.
  - New ftw function for fire tree walking, providing access to POSIX nftw.

  Bugs

  - Fixed issue in the UTF-8 encoding of Unicode strings, which TXR
    uses when calling API's that require char * strings:
    - U+DC00 pseudo-null produces the NUL character, which appears
      to terminate the char * string even if more characters follow,
      which is a problem.
    - Now, if U+DC00 occurs in a string that is being converted
      to UTF-8, an exception is thrown.
  - "Abstract" UNIX socket addresses properly supported on Linux.
  - defstruct:
    - now diagnoses use of nonexistent struct as supertype.
    - also fixed some minor diagnostic issues in defstruct.
  - symbol macros:
    - replacement forms were wrongly being expanded at bind time, and then
      possibly again at sustitution time.
    - now replacement forms are only macro-expanded during substitution.
  - glob function:
    - error callback hardened against continuation capture,
      absconding exits and re-entry of glob.
    - non-local exits allowed from error callback.
    - possible memory leak fixed.
  - Access to lib-version variable wasn't triggering its auto-load.
  - Fixed broken argument handling in umethod, also affecting
    umeth macro.
  - Invalid open mode strings in socket functions now diagnosed.
  - Fixed broken error handling in datagram case of sock-accept.
  - Source files processed by the load function, @(load) directive
    or by invocation of txr are now closed immediately after parsing.
  - TXR language:
    - fixed bug in data source opening logic leading to a mishandling
      of a case like @(bind x "a")text at top of script.



                                    TXR 137
                                   2016-03-30


  Features

  - Heads up: @(if) directive changes semantics.
    - no longer a syntactic sugar for @(cases)/@(require).
  - Rightmost-match variants added for various search
    functions: rfind, rpos, rmember and numerous others.
  - New macro lset for assigning consecutive elements of
    a sequence to multiple places.

  Bugs

  - Fix in lazy string implementation:
    - printing lazy string was not observing the string's limit
    - see limit-count param in lazy-str function.
  - Fix in error location reporting across macro expansions.



                                    TXR 136
                                   2016-03-20


  Features

  - I/O stream mode handling improvements:
    - "i" interactive mode specifies line buffering
    - New "l" and "u" mode letters for specifying line buffered
      and unbuffered mode on streams.
    - Decimal digit character in mode string specifies stream
      buffer size as a binary exponent with implicit 1024 multiplier.
    - Mode strings have a more permissive syntax; everything
      is optional with defaulting based on stream type.
  - Sockets:
    - sock-connect returns socket instead of useless t value.
    - New functions sock-recv-timeout and sock-send-timeout
      for setting the timeout options on socket.
      - I/O timeouts throw exception of type timeout-error
    - sock-connect and sock-accept have new parameter for
      timing out.
    - socket open mode is r+b by default, not r+.
  - TXR Extraction Language:
    - @(output) destination can be a stream object now
    - @(repeat) and @(rep) can now bind new variables, via
      extension to :vars syntax and semantics.

  Bugs

  - unget-byte sets errno to zero to avoid false errno
    association with failure.
  - Bugfix in @(repeat)/@(rep) internals: destructive manipulation of lists.
  - Tail streams honor all aspects of mode for re-opened
    stdio streams.



                                    TXR 135
                                   2016-03-10


  Features

  - The umask function is now provided.
  - Special new stream type for datagram sockets, allowing
    datagram programming to be very similar to and in some cases
    identical to stream socket programming.
  - A nil value in setenv now does unsetenv.
  - Improvements in sockets:
    - printed representation of sockets.
    - error messages.
    - error handling.

  Bugs

  - The get-string function closing a stream when told not to via a
    nil value of the close-after-p optional argument.
  - The setenv function had a similar bug, ignoring the overwrite-p optional
    argument being passed as nil.
  - Fixed cases of an incorrect error string from file streams returned by
    get-error-string.
  - Fixed gc-related instability caused by mishandling a field in an internal
    parser structure with regard to the ephemeral gc rules.



                                    TXR 134
                                   2016-03-01


  Features

  - Unhandled exceptions now unwind; so programs which terminate due
    to an unhandled exception have their cleanup performed.
  - Setuid support:
    - A setuid TXR executable supports setuid TXR scripts, even if
      the underlying OS doesn't allow setuid scripts.
    - When not running a setuid script, the setuid TXR executable
      drops privileges early in its execution, reducing the
      risk that it can be exploited.
  - New --eargs option, allows script name to be embedded among options
    in a hash bang line.
  - Networking support: TXR now supports IPv4, IPv6 and Unix socket
    communication.
  - Useful @(next nil) variant of @(next) directive to suppress unwanted
    treatment of a command line argument as a data source.
  - New functions expand-left and nexpand-left.

  Bugs

  - Expressions in @(require) were not being evaluated in the
    correct context.
  - Fixed destructive append behavior in append-each.



                                    TXR 133
                                   2016-01-21


  Features

  - New function, split*; like split* but keep empty pieces.
  - New function random-state-get-vec to get vector representation
    of random state.
  - vec-list now takes sequences as inputs, not just lists.
  - New functions base64-encode and base64-decode.

  Bugs

  - Bug in env-hash with values containing equal sign.
  - Bugfixes in partition* function.
  - More robust handling of invalid modulus values in rand
    and random.
  - Internal fixes in rand and random.
  - Serious regression in get-char on string input streams.
  - Missing syntax highlighting for some TXR symbols.
  - Bug in signal handling (synchronizing cached signal mask with
    OS signal mask) causing signals to be ignored after jumping
    out of a signal handling lambda with a dynamic control transfer.



                                    TXR 132
                                   2016-01-16


  Features

  - Unix crypt function exposed.
  - The identity function gets an alias named "use", for a
    readability improvement in certain functional coding scenarios.
  - The / function becomes n-ary, allowing forms like (/ 12 3 4).
  - New :mandatory keyword in until/last clauses, makes them a
    required match.

  Bugs

  - Fixed lack of location info for unbound variable error in dohash.
  - *print-flo-format* variable was affecting output of integers.
  - @(gather :vars ()) was behaving the same as @(gather); that is,
    as if :vars wasn't specified at all.



                                    TXR 131
                                   2016-01-13


  Bugs

  - Configuration with --valgrind now builds again.
  - Invalid lazy string optimization introduced in TXR 118
    has been re-worked. This affects the conformance of
    the @(freeform) directive to documentation.
  - When a macro declines to perform an expansion by
    returning the :form, the form was recorded as its own
    macro ancestor; now, nothing is recorded.
  - Fixed issues in how regex objects are printed:
    - Control characters and certain other characters were
      being dumped literally.
    - Now certain characters like newline print using
      the escape codes like \n.
    - Other control characters, as well as U+7F (ASCII DEL)
      and characters in the U+DCXX surrogate range are
      printed as hex codes.
    - [ and ] in a character class are properly escaped.
  - Fixed issue in string literals: semicolon character
    effectively disappearing after control character that
    is converted to hex escape.



                                    TXR 130
                                   2016-01-05


  Features

  - Interactive listener:
    - New Ctrl-X Enter command: submit line, but stay in history
      and advance forward by one line.
  - I/O:
    - New record-adapter function creates a "stream adapter" virtual
      stream object based on an existing stream.
      - The adapter changes the semantics of get-line to support
        delimiting of records via a regular expression (which is stored
        in the adapter), rather than the newline character.
      - With this, TXR can now process streams delimited in alternative
        was as if they were line-oriented.
    - New read-until-match function: extract characters from a stream,
      accumulated into a string, until a match for a regex occurs in
      that stream, and discard the match.
  - OOP:
    - In defstruct, function slots now initialized before other static
      slots regardless of order of specifiers.
  - Library:
    - New chr-digit and chr-xdigit functions: like chr-isdigit and
      chr-isxdigit, but returning the digit value instead of the
      t symbol.

  Bugs

  - Interactive listener:
    - Fixed recent regression in Tab completion: missing completion on special
      operators and macros.
    - Fixed Ctrl-X commands not recognized in a history search.
  - OOP:
    - Access to static slots of a lazy struct was triggering
      instantiation; this is fixed.
  - Library:
    - Recent change in chr-isdigit and chr-isxdigit return value
      semantics has been reverted, due to potentially breaking code
      which relies on (eql (chr-isdigit #\0) (chr-isdigit #\1)).



                                    TXR 129
                                   2015-12-30


  Features

  - TXR pattern language:
    - @(line) directive now works in horizontal mode
    - New @(data) and @(name) directives for capturing/matching
      raw data, and name of data source.
    - :counter in @(repeat)/@(rep) can now be given a starting value.
    - Quasiliterals in the pattern language are now evaluated as Lisp
      quasiliterals.
      - the compatibility mechanism provides the previous evaluation mode.
    - The same applies to @(output): variables now follow Lisp rules,
      similarly to variables in quasiliterals.
    - @(repeat) and @(rep) now "see" Lisp globals; no need to list these
      using :vars.
  - Lisp library:
    - chr-isdigit and chr-isxdigit now return the integer digit value
      when the test is true, rather than just t.
  - Object printing:
    - Lazy strings are now printed in a reasonable way, not shortened
      to the #<lazy-string ...> notation.
    - New special variales for global control over how floating-point
      objects are rendered: *print-flo-format* and *print-fo-format*.
  - OOP:
    - with-slots macro added.
  - Yet improved location and macro ancestry tracing in unhandled
    exception diagnostics.

  Bugs

  - Vim syntax highlighting files: fixed regression in genvim.txr
    causing missing identifiers.
  - Four-year-old bug in @(collect)/@(coll) fixed, causing the
    @(last)/@(until) clauses to be evaluated with an empty list
    of variable bindings whenever the main clause fails.
  - Fixed exception in @(freeform) directive when scanning from
    an interactive input stream.
  - Bugfixes in pattern language debug tracing (-v).



                                    TXR 128
                                   2015-12-19


  Features

  - Further refinement of function and macro coexistence:
    - symbol-function, fboundp and fmakunbound operate only on function
      binding.
    - new symbol-macro function.
  - The :whole and :form parameters now accept a destructuring parameter
    list as their argument, no longer insisting on nothing but a symbol.
  - OOP:
    - defstruct now supports a :postinit slot specifier, which allows
      additional actions to be taken after an object is constructed, and the
      slots are fully initialized.
    - make-struct-type has a new argument related to the above change:
      a <postinitfun> function.
  - Place manipulation macros now propagate ancestry information from
    the place forms on which they operate to the generate place-accessing
    operations, as if those operations were macro-expansions of the places.
    (Which they are not, at least not exactly). The benefit is that errors in
    those place access operations can consequently be traced to the original
    place forms, for more meaningful diagnosis.
  - dot notation like a.b.c now prints back as a.b.c rather than
    (qref a b c).
  - Doc:
    - HTML section numbers are now hyperlinks which jump back to the
      right place in the table of contents.
    - On jump-back, the table of contents expands sufficiently to
      reveal the target entry, if that is not already showing.

  Bugs

  - Fixed incorrect behavior of (replace seq val nil), also affecting
    replace-list, replace-vec and replace-str. The nil was wrongly
    treated as as a zero <from> argument (acting in complement to a
    missing <to> denoting the end of seq), instead of an empty <idx-list>.
  - Fixed broken assignment to [h x] when h is a hash and x is a vector
    or list.
  - Fixed dot syntax like a.b not recording source location info into
    the (qref ...) form when its constituents are atoms, such as symbols.
  - Fixed neglect to propagate macro ancestry information across
    non-macro code transformations.
  - Fixed situations in which the debugger fails to report the
    source file and line number.
  - Fixed annoying debugger behavior of stepping through the macro expansion
    time evaluations of a query by making that behavior subject to
    a new option (--debug-expansions). Debugger will now stop on
    the first line of the TXR language query like it used to.



                                    TXR 127
                                   2015-12-10


  Features

  - OOP:
    - defun can define methods now, using a compound naming syntax,
      as alternative to defmeth.
    - func-get-name function works on methods and produces compound name.
    - defmeth returns compound name, and so does defun when defining a method.
    - improved semantics in static-slot-ensure
  - Large file support: TXR now uses 64 bit file offsets in functions like
    seek-stream and truncate on Linux platforms where this is
    a compile-time switch.
  - regex-range now returns a range object.
  - Macros:
    - Improvements in macro expansion tracing for unhandled
      exceptions, or those caught in the REPL.
    - New macro-ancestor function for programmatically retrieving
      the form from which a given form was derived by macro expansion.
    - New mboundp and mmakunbound functions for inquiring
      about and removing a global operator macro binding.
    - Global operator macros can now coexist with functions of the
      same name.
  - Doc:
    - HTML man page now has a collapsible table of contents, thanks
      to Javascript embedded in the document.
    - Sections have been reorganized.
    - Smattering of corrections.

  Bugs

  - Fixed new struct types failing to inherit static slots that
    were added to ancestor types using implicit or explicit use of
    ensure-static-slot (such as methods defined outside of defstruct).
  - Fixes to the anaphoric ifa macro: the condition can be a dwim form, and
    with special handling.
  - Fixed incorrectly implemented less comparison for range objects.
  - Fixed crash in get-line when invoked on a closed file stream.
  - Fixed ftruncate not being detected and used on Solaris.



                                    TXR 126
                                   2015-11-29


  Features

  - New functions window-map and window-mappend for filtering sequences
    with a sliding window context surrounding the current element.
  - New macro define-accessor for easily extending functions
    to be accessors (supporting assignment).
  - Diagnostics for unhandled exceptions, and those caught in the REPL,
    now include a detail trace of the macro-expansion which created the
    form in which they originate.
  - Increased stack size on Windows (MinGW and Cygwin).

  Bugs

  - Regression in super function: when called with a struct instance, was
    returning its type rather than supertype.
  - Incorrect behavior (failure) in split and partition functions when index
    argument is a function, and returns nil.
  - Fixed regression in transpose function, causing it to be destructive.
  - Fixed sethash: it was returning a boolean rather than the stored value,
    as documented.
  - Improved clarity of error messages which identify destructuring mismatches
    in macro calls and macro-like binding constructs.
  - Fixed poorly informative diagnostic when defmeth is used on a nonexistent
    struct type.



                                    TXR 125
                                   2015-11-20


  Features

  - OOP improvements:
    - New uslot function and usl macro for functional indirection
      on struct slots.
    - New functors feature: define a lambda method for struct types
      which lets structs be invokd as function.
    - Lazy structs feature:
      - New lnew macro (and make-lazy-struct function) for lazily
        instantiating a new structure.
      - Self-referential, and mutually referential structures can
        be instantiated in one step using the existing mlet and
        lnew.
    - New Equality Substitution feature:
      - An equal method defined on a struct type allows objects to
        to be compared with equal or less, and to be hashed with hash-equal
        (and thus :equal-based hash tables).
      - The method simply returns an object which is used in place of
        the struct for the purpose of the comparison or hash.
  - TXR Extraction Language:
    - @(rep) now available as shorthand for @(coll :vars nil)
    - In @(next source), source can be a Lisp expression without leading @.
    - :to_html and :from_html filters now called :tohml and :fromhtml;
      old names will continue to work.
    - :tohtml filter now also translates ' (ASCII 39 apostrophe) to &#39;.
    - New :tohtml* filter, leaves quotes alone.
  - New butlast function.
  - New html-encode* function.
  - The last function is generic now, applying to strings and vectors.
  - New TXR_COMPAT environment variable, alternative to -C option.

  Bugs

  - Fixed missing autoload registration for meth, umeth and defmeth symbols.
  - Fixed spurious retention issues in various library functions like
    mapdo, preventing them from processing lazy lists in constant memory.
  - Fixed type hole in the equal function, which treated two COBJ objects of
    different types using a comparison function which assumes they are both
    of the same type.
  - Fixed buggy less function, which was comparing and ranking objects that
    should not be comparable according to the documentation.



                                    TXR 124
                                   2015-11-14


  Features

  - New iread function for reading an object from a stream
    in an interactive-friendly way.
  - Median-of-three pivot selection added to quicksort to
    avoid degenerate cases.
  - Scoping rule for implicit nil block in the for operator
    has changed: the block now surrounds the variable
    initialization forms.
  - New block* operator and functions return* and sys:abscond*,
    which allow blocks to be defined and referenced
    using symbols computed at run-time.
  - New function group-reduce for flexible decimation of a sequence
    to a hash table.
  - The (rcons x y) syntax is printed as x..y now.
  - nreverse handles strings and vectors now, and reverses them in place.
  - reverse handles vectors and strings in more efficient way,
    and can reverse lazy strings.
  - Functions revappend and nreconc added.
  - New *print-flo-precision* special variable for controlling precision
    applied when printing floating point objects.
  - New *print-base* special variable for controlling base in which
    integer objects are printed. (Only binary, octal, decimal and hex
    are supported.)

  Bugs

  - Fixed object printer throwing exceptions when meeting unexpected syntax
    in forms that have special printed notation like quote and whatnot.
    The correct behavior is to avoid the notation and print the raw syntax.
  - Fixed ~o format specifier, broken with respect to bignum operands
    in TXR 120, when ~b was introduced.



                                    TXR 123
                                   2015-11-06


  Bugs

  - Fixed regression introduced in TXR 115, in the search_regex
    function and functionality built on it.



                                    TXR 122
                                   2015-11-05


  Features

  - New type: range.
    - range is similar to a cons cell, but is an atom.
    - has two fields called from and to.
    - the dotdot syntax a..b  now produces a range, not a cons.
    - printed notation looks like #R(0 10)
    - related functions: rcons, rangep, from, to.

  - sys:capture-cont API altered to call/cc style: passes
    continuation to specified function when capturing,
    returns value when resuming.

  - New interface to delimited continuations: suspend macro.

  - TXR pattern variables now appear dynamic to embedded Lisp
    expressions, rather than lexical. The scoping rule is
    documented.

  - The yield and yield-from operators can omit the argument
    form, in which case they retrieve the value passed in from
    the resume function without yielding an item.

  - Architecture support: Power PC 64.



                                    TXR 121
                                   2015-10-30



  Features

  - TXR Lisp now has delimited continuations.
    - easy to use via obtain/yield macro operators.
  - New function truncate-stream for truncating files.
  - Reduced stack usage on glibc systems by shrinking unwind
    frames, achieved by replacing the 128 byte wide sigset_t
    type with a much smaller type.
  - The way place macros are expanded has improved, making
    them more useful.
  - Macro parameter lists have a :form keyword now for capturing
    the whole form.

  Bugs

  - Implemented missing second argument of zap macro.
  - Assignment to *listener-hist-len* in ~/.txr_profile was not
    correctly taking effect prior to loading history, causing
    truncation to 100 lines.
  - Fixed typo causing with-hash-iter macro not to autoload.
  - Fixed crash in hash-next.


                                    TXR 120
                                   2015-10-18


  Features

  - Structs:
    - Finalizers (specified by :fini) are now registered early in the
      object initialization (at a given inheritance level). This allows
      finalizers to clean up abandoned initializations.
    - If initialization of a struct is abandoned, the finalizers are invoked
      immediately, as part of unwinding.
    - New defmeth macro for defining methods outside of a defstruct.
    - New static-slot-ensure function for adding a new static slot to
      a struct (and its inheritance descendants).
    - static-slot and static-slot-set can take struct type name in place of
      struct type.
  - New functions hash-begin and hash-next, for iterating hash table,
    and with-hash-iter macro.
  - Listener:
    - TXR now launches listener if no arguments are given.
  - Exceptions:
    - New way of handling exceptions without unwinding: handler-bind and
      handle operators.
    - Introspection over exception frames: get-frames and find-frame
      functions can inquire about frames, and invoke-catch can transfer
      control to a chosen catch frame.
  - New ~b conversion specifier in format function for printing integers
    in binary.
  - The typecase macro has been added, similar to Common Lisp's.
  - Some functions have been renamed for consistency, but remain available
    under old names: list-vector -> list-vec, vector-list -> vec->list,
    chr-num -> chr-int, num-chr -> int-chr.
  - The sh function isn't implemented using the C library function
    system any more.

  Bugs

  - Fixed use of nonexistent functions in error handling cases
    of defstruct macro.
  - Fixed bug in the overflow check in the chk_grow_vec function,
    used by string-extend, the get-line function of many stream types,
    and string output streams.
  - Fixed unterminated format argument list issue affecting interactive
    listener. (Reproduced on Mac OS/X).



                                    TXR 119
                                   2015-10-10


  Features

  - Interactive listener:
    - New Ctrl-X Ctrl-R to insert entire previous line.
    - Word/Atom from previous line works relative to recalled history line.
    - New Ctrl-X Tab for substring-searching completion.
  - Empty loops can be interrupted by signals: (for () () ()) is now
    interruptible at the interactive prompt.
  - New umethod and umeth function for indirecting on a method in a way
    that is detached from an object instance.
  - Boa construction of structures can have optional arguments now.
  - copy and copy-str now copy lazy strings as lazy strings, rather
    than forcing to regular string.
  - New functions for sequence manipulation: take, take-while, take-until,
    drop, drop-while, drop-until.
  - New function ginterate for lazy generation which includes the terminating
    item.
  - New function expand-right for lazily generating a sequence in a roughly
    opposite way to a reduce-right reduction.
  - New function call-finalizers for explicitly invoking and clearing the
    registered GC finalizers for an object.
  - New functions clear-struct and reset-struct for clearing all slots
    of a structure to nil, or reinitializing a struct to default values,
    respective.
  - New function replace-struct for changing and slot contents and type
    of a struct to match an example object.
  - Missing promisep function added to test whether an object is a promise
    created by the delay macro.
  - New defex macro, to define exception subtype relationships out of TXR Lisp.
    (Previously available only in the TXR pattern language).
    - Also useful surrounding functions: exception-subtype-p,
    register-exception-subtype.
  - New macros for working with streams in lexical scopes:
    with-out-string-stream, with-out-strlist-stream with-in-string-stream,
    with-in-string-byte-stream, with-stream.
  - New with-objects macro for scoped finalization of objects,
    somewhat like destruction in C++.
  - Vim syntax highlighting file sets "lispwords" option for
    more accurate indentation of TXR Lisp.

  Bugs

  - Fixed symbol-function throwing error on builtin macros.
  - macro-time is now special-operator-p.
  - Named block around bodies of methods and functions declared
    in defstruct.
  - slot-p renamed to slotp (old name supported in compatibility mode).
  - Bug in structure initialization: boa arguments were applied first,
    before other initialiations, rather than last.
  - The conses function works on vectors and strings.



                                    TXR 118
                                   2015-10-01


  Features

  - Interactive listener:
    - Parentheses matching jump (Ctrl-]) now finds the closest parenthesis,
      bracket or brace if the cursor isn't on one already.
    - Tab completion recognizes .( and (( context in front of symbol
      being completed, and doesn't restrict to function names.
    - Parenthesis-matching "jump" is now performed on backspace also,
      if cursor lands on or next to a parenthesis.
    - Ctrl-A and Ctrl-E (or Home and End) keys have now have a useful behavior
      in multi-line mode, allowing a jump to the start/end of the current line
      as well as start/end of the edit buffer.

  - Optimizations in regular expressions:
    - In particular, prefix matches involving the complement operator now
      indicate termination rather than wastefully consuming the remainder of
      the string.
    - Algebraic reductions performed on regexes. In some cases, these
      reduce an expression which contains exotic operators such that it
      can be compiled to NFA.

  - Structures:
    - Structures can now have static slots: slots shared among all instances
      of the same type (but not other types, not even derived types).
    - Static slots are now the preferred the basis for implementing functions
      and methods.
    - The defstruct syntax has a richer syntax which lets static slots
      be expressed, as well as methods.
    - Construction and finalization code can be specified in defstruct.
    - Many new functions related to structures.

  - Optimization in lazy strings: forcing lazy strings is more efficient.

  - String input streams do not force lazy strings now.

  - The "matches nothing" regular expression represented in the
    abstract syntax by the object t now handled by regex printer,
    and rendered as [].

  Bugs

  - Fixed a silly delete-previous-word behavior in multi-line mode:
    not treating the line-break as a whitespace character that separates words.

  - Fixed various problems in screen update and cursor positioning behavior in
    interactive listener, affecting multi-line mode.

  - Fixed two bugs in the ifa/conda macros.

  - The return and return-from operators do not abort TXR when a label is not
    found, but properly throw an exception.

  - Garbage collection: if GC is triggered in response to a malloc
    delta, a full GC is now performed. This prevents runaway memory
    allocation behavior in code which manipulates large arrays, strings
    or integers.

  - Fixed strangely compounded error message issued in the situation that
    unbound variables occur in the TXR pattern language.

  - Various "internal error" situations in the regex module now throw
    exceptions. Consequently, TXR will not die if a bad abstract syntax
    tree is passed to the regex compiler.

  - Regex printer was throwing an exception when printing a character
    class containing \w, \s or \d.



                                    TXR 117
                                   2015-09-23


  Features

  - Interactive listener improvements:
    - Visual selection of text, with copy and paste:
      Ctrl-S, Ctrl-Q, Ctrl-X Ctrl-Q, Ctr-^.
    - Undo feature with separate undo per history line.
    - Security checks on ~/.txr_profile permissions.
    - Location reporting when exceptions caught.
    - Syntax errors pinpointed to line in multi-line entry.
    - Ctrl-X Ctrl-V "super verbatim" mode.
    - Temp file used by Ctrl-X Ctrl-E has .tl suffix now for
      correct syntax highlighting.
    - Ctrl-X <n> Ctrl-W: insert word from previous line.
    - Ctrl-X <n> Ctrl-A: insert atom from previous line
    - Delete to beginning of line or to end of line now limited
      to current physical line in multi-line mode.
    - Ctrl-X Ctrl-K to delete current physical line.
    - Visual Parenthesis matching works forward now as well as reverse.
    - Ctrl-] jump to matching parenthesis.

  - Unix group database functions added: getgrgid, getgrnam, getgrent.

  - New path-private-to-me-p function to detect whether a file
    is writable to users other than the owner.

  - New flatcar and flatcar* functions. Variants of flatten which
    handle improper lists and preserve nil atoms.

  Bugs

  - Correct tab alignment in multi-line.

  - Fixed screen untidiness on Ctrl-Z and Ctrl-C in multi-line mode.

  - sub function and [] indexing were not handling lazy string objects.

  - sub-str wasn't handling defaulted optional arguments correctly for
    lazy strings.



                                    TXR 116
                                   2015-09-17


  Features

  * Interactive listener improvements:
    * Ctrl-R reverse search has been implemented.
    * Tab completion now works anywhere in a line, not only
      at the very end.
    * Parenthesis matching: cursor jumps briefly to matching bracket,
      brace or parenthesis.
    * Multi-line mode, with proper history support for
      lines containing embedded line breaks.
    * Ctrl-C cleanly cancels completion, and navigation keys
      smoothly transition from completion to edit mode.
    * Ctrl-X Ctrl-E edits line in external editor.
    * Ctrl-Z suspend and Ctrl-L clear work in completion mode.
    * New :read command for parsing pasted material from terminal.
    * Dynamic resizing of the terminal is now obeyed (SIGWINCH signal).
    * A ~/.txr_profile file is now read on interactive start-up,
      and Lisp forms are evaluated from it.
    * multi-line mode and history length are configurable via special
      variables.

  * Removed arbitrary limit on regular expression size (number of states).

  * Small regexes are processed with a smaller memory footprint due to
    exact allocation of certain arrays and stack allocation is used
    in some cases instead of malloc.

  Bugs

  * Fixed memory leak of blank lines in listener.

  * Comment lines entered into the listener do not produce a syntax
    error and are entered into history.

  * Fixed memory leak in NFA regular expressions.

  * Fixed a counter wraparound bug in NFA regular expressions, resulting
    in incorrect operation after 4.2 billion state transitions (2**32
    characters fed to the same regular expression, whether in a single
    job or across multiple jobs.)

  * Addressed some minor issues in unwinding and signal handling.



                                    TXR 115
                                   2015-09-11


  Features

  * Sixth anniversary edition!

  * New REPL on Unix platforms: an interactive listener with line editing,
    history recall, completion and exception/interrupt trapping.
    This is started with "txr -i".

  * Improvements in error reporting.

  * New function, raise, for raising a signal, eliminating
    the (kill (getpid) sig) workaround.

  * New functions subtypep and typep for testing subtype relationships
    between types, and between an object and a type.

  * New abstract types usable in conjunction with subtypep and typep.
    For instance, integer and number are types. A fixnum is a subtype
    of integer, which is a subtype of number. Type hiearchy documented in
    detail.

  * The printed representation of function objects is much more
    informative than before.

  * The variable *args* is now not only bound when evaluating Lisp
    expressions from the command line (with -e and related options)
    but it is also modifiable.  Command line expressions can rewrite the
    remaining arguments by updating *args* and these arguments
    instantly take effect.

  * Some section restructuring in the documentation.

  * New functions for working with package objects: package-alist,
    package-name, package-symbols.

  Bugs

  - Fixed serious problem in implementation of signal handling:
    the function to manipulate the signal mask in a cached way
    wasn't actually calling into the OS to set the real signal mask.

  - Fixed another serious problem in signal handling: a Lisp function
    throwing an exception out of a signal handler would cause an
    imbalance in an internal signal reentry counter, causing later
    signal handling to stop working properly.

  - Fixed an assertion occurring in the Flex-generated scanner if the parsing
    of a stream is aborted by an exception, and then the parser is called
    again.

  - Fixed regression dating back to TXR 105: the TXR pattern language
    failing to use a "real-time" stream for standard input, when it
    is a TTY, thus breaking the specials upport for pattern matching
    into interactive input.

  - Removed an accidentally committed debug print, producing output
    in situations when a function is called with the wrong number of arguments.

  - Fixed (eval 'sym) reporting the unbound variable sym against the wrong
    source code location.

  - Fixed random state objects being of type *random-state* rather than
    of random-state. The earmuffed symbol was never intended.

  - The accessors fun, symbol-function and symbol-value were completely
    broken for use as syntactic places.

  - Fixed multiple evaluation of the slot argument when slot used as
    syntactic place accessor: (inc (slot x y)) now evaluates y only once,
    just like x.

  - Fixed another gaping bug in the finalization hook mechanism: objects
    being promoted into the tenured generation had their finalizers
    called while still remaining reachable.

  - Fixed the self-path variable not being bound when evaluating Lisp code from
    a .tl file or command line arguments like -e.

  - Fixed *args* not being bound when evaluating Lisp expressions from
    the command line with -e and related options.

  - Fixed missing :tointeger filter. It was actually registered under the
    misspelled keyword symbol :toinger, and never existed as :tointeger.
    It has actually been renamed to :toint.


                                    TXR 114
                                   2015-09-03


  Features

  ! Note: TXR code base converted to new way of handling variadic function
    (variable-length struct args, defined on stack).

  * New function shuffle: Fisher-Yates/Knuth on lists and vectors.

  * Numerous documentation improvements.

  * Improved diagnostic in situations when an error exception is
    thrown at code parse time, pinpointing file and line number.

  * New feature: structs! TXR now has typed data structures with named
    slots. Structures can be related by single inheritance, and
    single-dispatch OOP is easily expressed.

  * stat, lstat and fstat functions return a stat structure now.

  * New functions: time-struct-local and time-struct-utc return
    a structure instead of a list of fields.

  * Unix password database functions: getpwent, getpwuid, getpwnam.

  Bugs

  * Fixed regression: broken treatment of [hash x..y] place.

  * Fixed finalize function, which was found to be fundamentally broken.
    Advertized as a new feature in TXR 101, it now actually works.



                                    TXR 113
                                   2015-08-20


  Features

  ! Note: txr builds and works with Berkeley Yacc again.

  ! Note: txr is starting to make use of the alloca function.

  * regex-parse function allows unescaped slashes and treats them
    as verbatim characters, in recognition of slash delimiting being
    needed only by regex literals.

  * Better argument number mismatch reporting in certain indirect
    function call situations.

  Bugs

  * Serious quasiquote regression fixed (from TXR 110): function call
    syntax interpolated into a quasiliteral not working for TXR pattern
    language quasiliterals, when the function is called with exactly
    one argument; e.g. @(bind x `abc @(list 1)`).

  * Serious parser problem fixed affecting Lisp code being read from
    streams. The wrong kind of weak hash table was used to associate
    parsers and streams, causing a disruption when garbage collection
    kicks in, precipitating a false syntax error.

  * Nested meta-variable references now work in quasiliterals.  If a
    quasiliteral is nested in two layers of op syntax, it can use notation
    like @@@1 and @@@rest to reach the outer parameters, and so on.

  * Minor spurious retention issues addressed (garbage collection).

  * Numerous markup errors fixed in documentation (thanks to
    Dave Love of Fedora Project).



                                    TXR 112
                                   2015-08-14


  Features

  ! Note: the ChangeLog is discontinued. Description of changes, going
    forward, is maintained in git commit messages only, in a hybrid format
    which conforms to ChangeLog and git conventions at the same time.

  ! Note: txr doesn't work correctly if parse.y is built with Byacc.
    GNU Bison must be used. This will be addressed in the next release,
    hopefully.

  - Support for display width concept: identifying Unicode characters which
    occupy two print positions on tty-like display and printing devices.
    - Indentation, and field formatting in the format function obey display
      width, rather than naive string length.
    - The new display-width function calculates the display width of
      characters and strings.

  - The a..b syntax is slightly revised; it can occur outside of a list now,
    and in the terminating position of a dotted list. It correctly associates,
    so that a..b..c denotes (cons a (cons b c)).

  - New function clamp for clamping numeric and other values to a range.

  - New "qref dot" syntax: a dot flanked by expressions and no whitespace
    denotes a new syntatic sugar such that a.b.c.d denotes the form
    (qref a b c d), and a.b.(x y).z denotes (qref a b (x y) z).
    However, this qref syntax has no assigned meaning yet (coming soon).

  Bugs

  - Regression in format function introduced in 111 is addressed: geneating
    superfluous left padding when formatting non-numeric fields.

  - Bad consing dot syntax like (a . b c) and (a . b . c)
    is properly diagnosed instead of silently producing
    strange (though consistent) results.

  - Tokens with a package prefix but empty name like abc: are correctly
    handled now by interning a symbol with the name "" (empty string)
    in the given package.

  - Fixed some minor bugs in lexical analysis of floating-point constants:
    actual behavior was interpreting as valid certain forms that were
    documented as erroneous.

  - Fixed stream close bug in catenated streams.



                                    TXR 111
                                   2015-08-08


  Features

  - Nested structural objects (list structure, vectors, hashes) are now printed
    with line breaks and indentation.

  - Introducing global lexical variables, introduced with defvar
    and defparml. Global lexicals are not marked special, and so local
    bindings of the same symbols are ordinary lexicals and not dynamic.

  - Numerous variables in the library are now global lexical rather than special.

  - pi and e are now provided as %pi% and %e%, global lexical.
    The *pi* and *e* specials are retained, and obsolescent.

  - New hash-revget function for reverse lookup through hash tables.

  - New function func-get-name for obtaining name from function.

  - New ~! format directive for controlling hanging indentation.

  - format conversions now support ^ character for centering within
    a field.

  - Output streams now support indentation. This is used by the object
    printer and by the ~! format directive, and also exposed by
    a group of new functions like set-indent-mode.

  - TXR Lisp documentation sections re-arranged for better organization,
    and other improvements in documentation.

  - Improvements in matching error exceptions to source code location,
    and some other diagnostic improvements.

  - New wrapper functions for Unix lstat and fstat for inquiring about the
    properties of symbolic links, and open files.

  - New Unix wrappers for uid/gid functions: getuid, setuid, etc.

  - New functions for conveniently testing for file existence, type, ownership
    and permission, and relative age.

  - Debugger won't step into auto-loaded library code now, unless
    requested with new --debug-autoload command line option.

  Bugs

  - Fixed parsing bug in txr-case macro: throwing error on correct syntax.

  - Discovered that an object initialization pattern believed to be
    correct is flawed in the face of generational GC. Fixed instances
    in hashing and regex module.

  - Documented special variable *args-full* is now actually implemented.
    It was implemented as *full-args*, which is retained, but obsolescent.

  - Operations on an output string stream which overflow throw
    exception instead of returning nil.

  - Fixed incorrect handling of negative field widths in format,
    when specified dynamically via *.



                                    TXR 110
                                   2015-07-25


  Features

  - New relational predicate functions hash-subset and hash-proper-subset.

  - New functions hash-from-pairs and hash-list.

  - Improvements in quasiliterals:
    - compound @@ now supported on numbers and symbols, improving utility of
      quasiliterals in multiply nested op syntax.
    - \@ escape introduced for encoding literal @ in quasiliterals.
    - @<num> notation allowed in brace variables (more of a bugfix).

  - Optional trailing semicolon punctuator supported on hex and octal
    characters in string and quasiliterals, like it already is on hex and octal
    characters in the TXR pattern language.

  - The op syntax positional arguments @1, @2 ... and @rest are now
    syntactic places: they can be assigned, etc.

  - Powerful new binding macros placelet and placelet* for creating lexical
    aliases for syntactic places with once-evaluation semantics.

  - The "it" variable in the anaphoric ifa is now a place if the form that
    it denotes is a place. The place is evaluated exactly once no matter how
    many times the it variable is accessed or updated in its scope.

  - Hash-bang support in .tl files.

  - With only a few sensible exceptions, most unimplemented stream operations
    now throw exceptions, rather than silently doing nothing.

  - Improved printed representation of stream objects.

  - New split function similar to partition, but keeps empty subsequences.

  - Deletion of a (cdr ...) place now has different semantics, symmetric
    with deletion of a (car ...) place.

  - The accessors caar, cadr, cdar, cddr, ... are all provided now, in
    all combinations down to five levels deep.

  - The functions second, third, fourth, ... are all accessors now,
    and are provided up through tenth. They work with vectors and strings.

  - New feature, "place macros": special macro expansions which apply
    only to syntactic place forms, making it a cinch to define
    to define new places in situations when they are expressible as a
    syntactic transformation to existing places.

  - The nthcdr function from Common Lisp is introduced, with the
    added functionality that it behaves like an accessor.

  - New with-resources macro for block-scoped acquisition and release
    of multiple resources.

  - Backslash-newline continuation in word list listerals (WLL-s) and
    quasiword list literals (QLL-s) now separates words. An unescaped
    newline is not allowed.

  Bugs

  - TXR 97 regression in quasiliterals fixed: `@{(expr) modifier}` ignores
    modifier whenever (expr) is an expression that undergoes expansion.

  - Fix in printed representation of a stdio stream.

  - define-modify-macro was not registered for auto-loading.

  - Fixed broken unget-char and unget-byte on catenated streams.

  - Fixed broken lexical analysis of consecutive top-level forms,
    like 4(x) where one call to the parser consumes 4(, so the
    next call sees x).

  - Fixed bug in print and pprint: wrong return value when printing a dwim
    form. These functions must always return their leftmost argument.



                                    TXR 109
                                   2015-06-21


  Features

  - New anaphoric macros ifa and conda.

  - New function have, synonym of true. Usefully expressive with anaphoric ifa.

  Bugs

  - equal-based hashing function is improved so list and vector permutations
    do not collide to the same value.

  - cat-str function detects overflow in the calculation of the total
    string length to allocate, and throws an exception.

  - Fixed neglected null termination in mkstring function.

  - Fixed garbage collector crash introduced in TXR 108, when traversing
    syntax_tree member of the parser_t structure.



                                    TXR 108
                                   2015-06-13


  Features

  - POSIX poll function exposed.

  - Entirely new macro-based framework for syntactic places (forms denoting
    locations that can be assigned): better featured, extensible than
    previous hard-coded hacks.

  - New macro: define-modify-macro.

  - New pset operator: assign to places in parallel.

  - rplaca and rplacd handle vectors and strings.

  - replacement sequence in replace function can now be a vector.

  - symbol-value retrieves bindings of symbol macros.

  - boundp returns true for symbol macros.

  - New functions: makeunbound and fmakunbound.

  - New concept: deletable places: locations that can not only be accessed, but
    which can be deleted. Existing del operator which contained special case
    hacks is now powerful, general macro that can delete any deletable place.

  - New defparm operator to accompany defvar.

  - symbol-function, symbol-value and fun forms are assignable places.

  - Debug instrumentation code made light weight, leading to big improvement
    in the execution speed of TXR Lisp.

  - New functions catenated-stream-p and catenated-stream-push.

  - New function: load for loading TXR Lisp files. TXR Lisp programming can
    now take place using multiple files containing code that doesn't have
    to be wrapped with @(do ...).

  - @(load) and @(include) directives can also load TXR Lisp now.

  - TXR files which have a .txr suffix can be invoked without the suffix now;
    this is automatically resolved.

  - New --lisp command line option makes TXR source files which have no
    filename suffix be treated as TXR Lisp code rather than TXR Pattern Language.

  Bugs

  - Fixed exception being thrown when trying to print (lambda . atom).

  - Dangling unquotes and splices now receive source location info.

  - Fixed memory corruption caused by disabling garbage collection
    for too long.

  - Better syntax checking in flet, labels, lambda, defun, quote.

  - Addressed clash between flip operator and flip function by renaming
    latter to flipargs.

  - Fixed regression in Verison 106 causing apply calls not to diagnose
    the too many arguments case, and allow a stack overrun.

  - chr-str-set checks for literal strings, which cannot be modified.

  - Fixed runaway recursion in keep-if* and remove-if*.

  - Fixed mismanagement of dyn_env variable leading to spurious
    retention of memory in TXR builds configured without debugger support.
    (Bug exposed by the lighter weight debug support.)

  - Critical bugfix in handling of hashes having both weak keys and values,
    leading to memory corruption.



                                    TXR 107
                                   2015-04-26


  Features

  - Change in representation of promise objects. The force function
    now detects recursion and throws an error.

  - New mlet macro: a step beyond Scheme's letrec.

  - A trivial optimization in the keywordp function more than doubles
    the interpretation speed of TXR Lisp.

  Bugs

  - Fixed regression in the garbage collector introduced in October 2014,
    TXR 100. This would cause runaway memory growth, due to the garbage
    collector creating unnecessary new heaps.



                                    TXR 106
                                   2015-04-21


  Features

  - New function tprint; like pprint but prints lists of strings as
    lines of text.

  - New stream opening option letter "i" for marking streams interactive.

  - New command line option -n which makes standard input noninteractive
    even if it is a TTY.

  - New command line option -P which is like -p but based on pprint.

  - New command line option -t for printing Lisp value using tprint.

  - Stream argument in get-lines is optional, and defaults to *stdin*.

  - The Unix fork and wait functions are exposed for use.

  - New function open-fileno for opening a stream on a Unix file descriptor,
    and fileno for retrieving a file descriptor from a stream which has one.

  - New functions dup (interface to Unix dup and dup2), chmod, exec
    and pipe.

  - New exit* function which calls _exit.

  - Added getenv, setenv and unsetenv functions for environment manipulation.

  - New operator zap for overwriting a place with nil, and returning its
    prior value: good for losing a reference to an object while passing
    it to a function, and other uses.

  - New whilet (while + let) macro for variable binding plus iteration.

  - New iflet and whenlet (if + let, when + let) macros for variable binding
    plus conditional evaluation.

  - New while* and until* loops which unconditionally execute one
    iteration.

  - New dotimes macro for simple iteration.

  - New lcons macro for writing expressive, concise code around lazy conses.

  - Brace variable notation can now contain quotes and quasiquotes.

  - Quasistrings can contain quasiquotes: `prefix @^(,x ,y) suffix`.

  - Fixed regression introduced in TXR 81, causing the argument parts of
    brace variables embedded in quasistrings to disappear.

  - The backslash in regular expressions can now only be used for recognized
    escape sequences, or for making regex special characters literal. If it is
    applied to any other character, it is diagnosed as an error.

  Bugs

  - Fixed stack array overrun in apply function.

  - The int-str function was recognizing the 0x C language convention in base
    16 conversions. Also, an error is now thrown on bases outside of the
    range 2-36.

  - Eliminated nuisance error message issue from the Makefile about git not
    being found; git is properly detected in configure.

  - Streams opened on TTY devices are not automatically marked as interactive.
    This is done only for the *stdin* stream on startup.

  - The ~X specifier in format was printing in lower case just like ~x,
    for bignum arguments.

  - Addressed spurious retention (garbage-collection-related issue) in
    function application.

  - Parser now diagnoses trailing junk in hex, octal and binary literals,
    like #xAD0Z, #o7778 or #b011003.

  - Fixed character escaping issues in open-process on Windows.

  - Fixed bug in error reporting, causing TXR sometimes to report that
    an error was thrown out of a form, when it wasn't in fact that form.

  - Fixed bug in the printing of regular expressions: empty expressions
    like #// or expressins with empty subexpressions like #/a|/ would
    result in an exception.



                                    TXR 105
                                   2015-03-14


  Features

  - New function lexical-lisp1-binding for improved macro-time introspection of
    environments.

  - New functions pad and weave.

  - New regex functions search-regst, match-regst and match-regst-right,
    to complement search-regex, match-regex and match-regex right.

  - Improved error reporting, particularly for errors ocurring during
    the expansion of a macro.

  - Streams have persistent error state. New functions: get-error,
    get-error-str and clear-error.

  - New ignerr macro for trapping exceptions of type error, and converting
    them to a nil return value.

  - New function ensure-dir: creates a directory in the filesystem,
    with all parent directories also created as necessary, and doesn't
    complain if the directory already exists.

  Bugs

  - Bugfixes in append* function: lack of error handling and inappropriate
    forcing of infinite lists in some circumstances.

  - Bugfix in match-regex-right: zero length matches must return zero rather
    than nil.

  - Fixed memory leak in open-process and run on POSIX platforms.

  - Fixed memory corruption bug in run function on Windows platform.



                                    TXR 104
                                   2015-02-08


  Features

  - Symbol macros are now shadowed by lexically scoped functions, when
    referenced from the interior of a form which uses Lisp-1 semantics (a []
    bracketed form, a form based on the op family of operators, or explicit use
    of the dwim operator).

  - New function, abort.

  - TXR now doesn't terminate abnormally (abort) on unhandled exceptions, but
    only terminates unsuccessfully. This provides a better experience on
    the MinGW-based Windows target, where we get an annoying dialog box on
    abort.

  - New *uhandled-hook* variable can be used to register a user-defined
    function which is called when an unhandled exception occurs.

  - New arithmetic function, trunc-rem.

  - When the numbered arguments of partial application under the op family of
    operators are interpolated into a string quasiliteral, modifiers may
    now be applied. For instance (op prinl `@{1 20} @{2 20}`) denotes
    a function which prints its two arguments in twenty-character-wide fields
    separated by a space.

  - Improvements in Windows installer: reduced broadcast delay in registerting
    environment variable. Improved messages in this area.

  - A txr-win.exe can be built now which avoids creating a console window.
    This is included in the installer.

  Bugs

  - Fixed bug in quasiliteral string evaluation in TXR Lisp, in conjunction
    with op arguments like @1, @2, ...  When a value interpolated from
    one of these arguments looked like a form, it was mistakenly subject to
    recursive processing and variable substitution as if it were part of
    the quasiliteral target syntax.

  - Fixed a serious bug in the op macro and all related operators like do
    and ap, in the handling of situations with missing argument numbers
    was broken: such as when @3 is referenced, but not @1 or @2
    (which must generate a function of at least three arguments, which
    ignores its first two). This key feature was discovered to be utterly
    broken.

  - Fix in internal representation of exceptions: (throw 'x "foo") is now
    the same as (throwf x "foo").



                                    TXR 103
                                   2015-02-02


  Features

  - New functions lexical-var-p and lexical-fun-p allow macros to
    inquire whether symbols are known to the macro-expander as
    lexical variable or function binding.

  - get-string now closes the stream after obtaining a string.
    It has a new optional argument which can defeat the behavior.
    The -C option can be used to request the old behavior.

  - New function, constantp.

  - New functions callf, mapf, dup and flip for more power and flexibility
    in function-combining expressions.

  - New function width, for computing the bit width of signed and
    unsigned integers.

  - New function sign-extend, for converting an a two's complement
    bit field of any width into the corresponding integer value.

  - Windows executable (MinGW and Cygwin) now has an icon and
    meta-data like ProductVersion and FileVersion.

  - MinGW-based Windows build is now distributed via an executable installer
    instead of a ZIP file.

  Bugs

  - Fixed regression introduced in 102, in the fix to the make-like
    function.  A one element list being converted to a string was treated
    as an empty list, leading to empty string.

  - Fixed small bug in macro argument list processing. The colon symbol
    was treated as "this argument is missing" for required arguments also,
    rather than just for optional arguments.

  - Fixed a bug in the code expander's handling of macro parameter lists.
    It was not recursing properly over nested patterns occuring in optional
    arguments, and throwing errors on keywords like :env present in
    the optional argument parts of macro parameter lists.



                                    TXR 102
                                   2015-01-13


  Features

  - merge function becomes generic: works over sequences rather
    than just lists.

  - New function glob is provided on platforms which have the Unix
    C library function of the same name.

  - New functions plusp and minusp. zerop accepts character argument.

  Bugs

  - Fixed incorrectly implemented horizontal flavor of the
    @(trailer) directive.

  - Fixed a bug in the make-like function which has consequences for
    the results of numerous sequence functions. This bug causes functions
    to return an empty list when the expected result is an empty string.
    For instance [mapcar identity ""] now returns "", consistent with
    [mapcar identity "abc"] returning "abc". Previously it returned nil.

  - Fixed a serious bug affecting the OS X port. The llvm-gcc compiler
    was discovered not to be consistently aligning wide character string
    literals on four byte boundaries, even though wchar_t is four bytes wide.
    As a workaround, a very similar trick is usd as what is used to handle
    literals on Windows, based on the assumption that we *can* depend
    on two-byte alignment. The bug leads to a failure of the OS X port
    of TXR to support the -p and -e options, for instance: txr -p '(+ 2 2)'.



                                    TXR 101
                                   2015-01-01


  Features

  - Finalization support in the garbage collector. Use the finalize
    function to associate a function with an object which is called
    when that object is found to be unreachable.

  - iff function can now be called with just one argument.

  - New function chand.

  - New macros opip and oand.

  - The min and max functions are more generic by using the less function
    instead of the < function.

  - The less and greater functions are variadic now.

  - Select accepts a function in place of the index list.

  - Arguments of where function reversed, with backward compatibility support.

  - New functions succ, ssucc, sssucc, pred, ppred, pppred for calculating
    small deltas.

  - New functions wrap and wrap* for clamping a number into a given range,
    with modular wrapping semantics.

  - New function sort-group for sorting and partitioning a sequence in
    a single operation.

  - New function in for generic membership testing over any kind of sequence
    or hash.

  - copy function extended to copy random state objects.

  - New function unique, which generalizes uniq.

  - New function aret: apply version of ret.

  - Build system improvements: debug and optimized TXR built at the same time,
    dependencies handled in a cleaner way, tidy make output.

  Bugs

  - Fixed incorrect registration of repeat function, lacking support
    for its optional argument.

  - Removed dependency on useless Flex library (libfl).

  - Overflow arithmetic fixes in some array resizing logic.

  - Incorrect argument defaulting in iff function

  - Garbage printed in type mismatch diagnostic in sub, ref,
    refset, replace, update and search_list.

  - Behavior of splitr-str was undocumented for the case of the empty
    separator string and was inconsistent.

  - The set-diff function was not handling nil elements.

  - The toint function identified itself as tofloat in error messages.

  - The toint and tofloat conversions conveniently treat a character as a
    string of length one.

  - Added missing documentation that make-random-state can take an existing
    random state and clone it.

  - Also, make-random-state was incorrectly doing additional scrambling after
    copying an existing random state.

  - Simple lazy streams now close a stream when it runs out of data.

  - Catenated streams close each stream that is popped from the list due
    to running out of data.

  - Fixed bug in replace-str and replace-vec: when the argument was an
    index list that was lazy and infinite, it was being forced, causing
    an infinite loop and exhaustion of memory.

  - The partition* function was found to be buggy.

  - Separate directory build issues fixed.



                                    TXR 100
                                   2014-10-22


  Features

  - New functions: chr-isblank and chr-isunisp

  - New generic less and greater functions, which are also used as
    default functions in sort, find-max, max-pos, and others.

  - New directives @(line) and @(chr) for binding or asserting the current line
    number or character position.

  - Lisp expressions allowed on left side of @(bind) and @(rebind) now.

  - New function lcm (lowest common multiple).

  - The gcd function now takes zero or more arguments instead of exactly two.

  - New @(include) for parse-time loading of code, useful for loading macros
    which are needed later in the same file.

  - Beginning of library external to TXR executable: macros txr-if, txr-when
    and txr-bind for more convenient access back into the pattern
    language from TXR Lisp.

  - New combinator function notf for negating a function.

  Bugs

  - Fixed December 2011 regression affecting @(freeform) directive.

  - Fixed GC-safety bug in abs-path-p function.

  - Fixed breakage in scanner and parser introduced in August.
    Caught by C++ compiler.

  - Fixed inappropriate printed rendering of list objects produced by
    interpolated TXR Lisp expressions in @(output) blocks, and in
    the quasiliterals of the pattern language. (TXR Lisp quasiliterals
    not affected.) Users who depend on the old behavior not wanting
    to fix their programs can use --compat 99.

  - Bugfix in the gcd and lognot functions: neglecting to normalize some
    bignum result to the fixnum type.

  - Bugfix in @(eof) directive: not matching the end of interactive
    streams.

  - Fixed abort due to assertion going off when GC is disabled and the array of
    new generation objects runs out of space. This could happen during
    large parses.

  - Fixed parser stack overflow and inefficiencies when handling large TXR
    programs.

  - Bugfix in match_fun causing memory accesses to automatic storage
    that has been released, as well as an invalid longjmp.

  - Hash table reorganization is prevented during hash table traversal,
    so existing items are not skipped or visited twice.



                                     TXR 99
                                   2014-10-05


  Features

  - Variables in the pattern language can be bound to regexes, in
    which case they perform regex matches when matched against
    input.

  - Representation for compiled regexes is streamlined.

  - Regex objects now print in regex notation.

  Bugs

  - Fixed August 11 regression affecting 96 through 98: broken matching of
    unbound variables followed by bound variables.

  - Fixed one more problem with andf function: (andf) not returning t. 



                                     TXR 98
                                   2014-09-26


  Features

  - New numeric constants giving pi, e and various limits of floating point
    representation.

  - New syntax-error exception type; syntax errors in expressions passed
    on the cmomand line with -p or -e throw exception how instead of silently
    producing nil.

  - New --gc-delta option and gc-set-delta function related to
    bugfix below.

  - New -C/--compat option for specifying compatibility.

  - New functions: partition and partition*.

  - Revamped documentation: nicely formatted with fonts and section numbering;
    HTML version uses proportional font now, and has internal hyperlinks.

  - Exception names like file_error have been renamed to use a dash
    like file-error.

  Bugs

  - Fixed bad memory performance when the program works with large
    heaped objects, by making GC aware of this memory.

  - Fixed broken return value semantics of orf and andf combinators.



                                     TXR 97
                                   2014-08-29


  Bugs

  - A few GC-related fixes after code review.

  - Fixed @(load), broken in TXR 94.

  - Fixed broken @{var mod} syntax Lisp quasiliterals, broken in TXR 96.



                                     TXR 96
                                   2014-08-14


  Features

  - Big change in pattern language in the variable binding logic.
    When unbound variables are followed by directives, then the full right hand
    context to the end of the line is used to determine the binding.

  - Internal functions related to tries exposed: trie-lookup-begin,
    trie-value-at, trie-lookup-feed-char.

  Bugs

  - Fixed bug in ret operator: was generating fixed arity functions
    rather than n-ary as documented.



                                     TXR 95
                                   2014-08-07


  Bugs

  - Fix major regression: bad syntax causing crashes in parser.



                                     TXR 94
                                   2014-08-05


  Features

  - New functions: giterate, partition-by, uniq.

  - reduce-left and reduce-right correctly work on strings and vectors.

  - quasiquote splices can now occur in string quasiliterals, directly
    as `xyz @,foo`,  `xyz @{,foo}`, `xyz @,(foo)` etc. Previously this
    syntax was rejected, requiring workarounds like (let ((x ,foo)) `xyz @x`).

  - POSIX functions exposed: getpid, getppid, kill, setitimer, getitimer.

  - The parser is now re-entrant. This means that macro expanders can
    safely recurse into the parser, for instance with regex-parse
    or read.

  Bugs

  - @(output) blocks were discovered not to be applying filters to the results
    of embedded TXR Lisp evaluations.

  - n-perm-k function was broken for values of k equal to 1.

  - Fixed situations when exceptions with bogus messages are issued when the
    arithmetic +, - and * functions are called with wrong type arguments.

  - Fixed grossly incorrect documentation of the repeat function, to
    reflect actual syntax and behavior.

  - Fixed situations in which some signal handlers that don't need to
    execute on a separate stack might do so.

  - Put in a guard against async signal nesting: a situation when
    an asynchronous signal handler performs some blocking operation
    which enables async signal handling triggering re-entrancy.

  - Fixed platform-dependent behaviors in random number seeding
    (make-random-state function).



                                     TXR 93
                                   2014-07-22


  Features

  - New list munging functions interpose, mapdo, and juxt.

  - New macros caseq, caseql and casequal based on Lisp's case construct.

  - New math function log2 for computing base 2 logarithm.

  - New function get-lines for obtaining list of lines from a stream.
    Actually this is not new; it is a nice synonym for lazy-stream-cons.

  - New functions put-lines and put-strings.

  - Missing function lconsp added for testing whether an object is
    a lazy cons.

  - Documented existing function hash-construct.

  - search-str now supports a negative starting position, which counts from the
    tail of the string.

  - The division function / can now be used with one argument, denoting
    the reciprocal operation.

  Bugs

  - Bindings created using -D command line option are now visible to code
    executed via -e or -p later in the command line.

  - Fixed broken @(eol) directive; was behaving as a complete match, so that
    subsequent directives are ignored.

  - Obscure bug-fixes in @(do) and @(require), involving code that invokes
    pattern funcions, and the visibily of bindings.

  - Fixed hash-construct so it correctly works on an empty vector.

  - Alternative stack (sigaltstack) is now automatically used for SIGBUS
    handlers, not only SIGSEGV.



                                     TXR 92
                                   2014-07-11


  Features

  - New operators ado and ido.

  - New command line option --license.

  - Long overdue flet and labels operators for lexical binding in the function
    space, added as macros.

  Bugs

  - apf and ipf functions fixed.

  - Uninitialized variable bug fix in select function
    and in the index list case of replace-list.



                                     TXR 91
                                   2014-07-02



  Features

  - @(load `@stdlib/ver`) brings in a definition of a new variable
    called *lib-version* which lets programs check what version of
    the library they are using.

  - New functions where and sel for working with multiple indexes
    into a sequence.

  - New function seqp for testing whether an object is a sequence of any type.

  - New functions pos-max, pos-min, find-max and find-min.

  - New character constant #\pnul denoting the U+DC00 code
    (TXR's  "pseudo null").

  - New function tuples for reorganizing a sequence into tuples.

  - New functions true and false, expressive in applicative programming:
    for instance [all true list].

  - New functions member and member-if.

  - New function multi for applying a one-sequence operation to
    parallel sequences.

  - New functions tf, nilf, retf, apf, ipf.

  - New macros ret, ip and ap.

  - New function iapply for applying improper lists.

  - New functions transpose and zip.

  - New functions tok-where and range-regex.

  - New function bit for testing bits.

  - [] indexing now allows element extraction by index list,
    as well as assignment by index list, increasing the "slicing power".

  Bugs

  - Fixed reliance on leading slash as indicator of absolute path in @(load).

  - Fixed breakage in range and range* function (regression introduced
    in TXR 89).

  - Fixed bug in dwim operator: Lisp-1 evaluation semantics being propagated
    into nested forms, contrary to documentation.

  - Line number of error correctly reported in some situations in which
    it previously wasn't.

  - Fixed macros not being expanded inside quasiliteral brace notation.

  - Fixed broken last function.

  - Fixed broken bignum bit operations, not handling negative values
    properly.

  - Fixed reversed logic of logtest function.

  - Fixed some memory leaks in MPI bignum integer operations.

  - Documentation fixes.



                                     TXR 90
                                   2014-06-11


  Features

  - TXR has been ported to FreeBSD 9 and Solaris 10. These operating
    systems are officially supported going forward.  TXR's configure
    and build system has better portability support as a result.

  - call operator is a function now, like it should be.

  - Traling backslash in a dynamic regex is rejected as an error.

  - TXR no longer automatically prints out the bindings; this must be
    requested explicitly with -B. The -a and -l options now imply -B.
    The -b option for suppresing the automatic printing of bindings
    is deprecated.

  - New --args option, allows multiple logical command line arguments to be
    encoded in one physical argument which is useful in conjunction
    with very limited hash-bang (#!) scripting mechanisms on some systems.

  - New variable "stdlib" which expands to a path in the TXR installation.
    This will allow inclusion of standard modules. The stdlib variable
    automatically tracks relocation of the TXR installation.

  - New function for searching sequences for substrings: search.

  - New functions nullify and make-like for easily adapting list processing
    functions to correctly work on vectors and strings.

  - match-str function can now match from the end of a string, at various
    negative offsets.

  - New string comparison functions: str=, str<, str>, str<= and str>=.

  - string-lt function deprecated, replaced by str<.

  Bugs

  - rplaca and rplacd now return the cell rather than assigned value,
    and the return values are now documented.

  - Fixed a widespread bug which occurs when empty strings and vectors
    are treated as lists, due to the fact that they are not equal to
    the nil object.

  - Fixed completely broken string-cmp function, and changed its name
    to cmp-str.



                                     TXR 89
                                   2014-05-11


  Bugs

  - The eql function was not handling floating-point values correctly.

  - The range and range* functions internally use numeric comparison for end
    test rather than eql, so that they can step through floating-point values,
    but use an integer boundary, or vice versa.

  - Fixed broken default argument handling in get-line, get-char and get-byte.

  - The functions ref, refset, replace, and update (and the DWIM brackets
    syntax based on them) were not handling lazy strings.

  - Fixed a bug in the pattern language: when a variable ends up bound
    to the empty string, a literal empty string object was used, and
    that was not handled in the matching language. Best illustrated
    by the test case "echo : | ./txr -c '@a:@a' -".



                                     TXR 88
                                   2014-04-04


  Features

  - New TXR Lisp macros: while, unless, until.

  - New functions empty and last.

  - copy and length functions take hash tables now.

  - Word list literals and word list quasiliterals.

  - Big improvements in efficiency of generational garbage collection.
    Situations when a backpointer to a fresh object is stored into a
    mature object now are precisely identified, eliminating GC pressure
    caused by conservatively wrong guesses.

  - TXR is now configured to build with Generational GC by default.

  Bugs

  - copy and length functions handle lazy strings now.

  - time-string-utc on Linux now renders %Z strftime code as "UTC" rather than
    "GMT". Not our issue: this is a workaround for library behavior.

  - Generational GC fix: a number of functions which mutate state weren't using
    the proper set macro.

  - Generational GC fix: the gc_mutated function was not correctly implemented
    and could cause reachable objects with their GC reachability flag to
    continue to be set after GC is done.



                                     TXR 87
                                   2014-03-22


  Features

  - New convenience functions tofloat, toint: convert string or number to
    integer or floating-point.

  - New macro: when.

  Bugs

  - int-flo function was failing on negative numbers.

  - Fixed long-standing syntax issue: directives of the pattern matching
    language being syntactically recognized in the @(output) clause and
    in string quasiliterals, interfering with the ability to invoke Lisp
    forms based on the same symbols. This issue really "hit home" with
    the recent introduction of the @(if) directive, causing
    @(if expr then else) to suddenly be inaccessible in @(output) and
    quasistrings.



                                     TXR 86
                                   2014-03-16


  Features

  - Exposed the implementation of tries to user code.

  - New functions: html-encode, html-decode.

  - New prof operator and pprof macro for simple profiling: time spent and memory
    allocated over the evaluation of an expression.

  - New functions sh and run for running system commands.

  - If available, sigaltstack is used when the program registers a handler for
    the SIGSEGV signal, allowing TXR programs to catch stack exhaustion and
    recover by throwing an exception.

  - New syntactic sugar in the pattern language: @(if)/@(elif)/@(else)/@(end),
    which works by transformation to a pattern involving @(cases) and @(require).

  - The @(empty) directive which plays a role in @(output) blocks has a new meaning
    in the pattern language for denoting an explicit empty match.

  Bugs

  - Fixed severe performance problem with regex on long strings, caused by feeding
    characters to the regex machine past the point that it is clear it will not
    accept any more.

  - Fixed broken horizontal matching under @(freeform) on long lines, due to bugs
    in the handling of the memory-saving optimization which consumes the prefix of
    the lazy string as scanning progresses.

  - Fixed breakage in sub-str over lazy strings.

  - Fixed possible crash in @(trailer) directive.

  - Fixed memory leaks on open-process: one that happened on every call, and one on
    failure of the fork function.

  - Fixed pipe-close deadlocks occurring in code that opens numerous pipes; solved
    by setting the close-on-exec flag on the pipe descriptors.

  - Fixed faulty argument defaulting logic in the functions: iffi, regex-parse,
    lisp-parse, regex-compile and Windows version of open-process.

  - Fixed regression in the random number module, causing the random function to
    ignore the seeded random state passed in as an argument, and rely on the global one.

  - Fixed a bug in a rarely used form of the backslash line continuation.

  - Fixed buggy argument quoting in Windows version of open-process.

  - The gc on/off state is now saved and restored as part of unwinding, so if
    code that turned off gc throws an exception, gc will be turned back on
    at the catch site.

  - Fixed incorrect calculation of malloc upper and lower boundaries, affecting
    the correctness of generational garbage collection.

  - In open process, if fdopen fails, kill the process more gently with SIGINT
    and SIGTERM rather than SIGKILL, and wait on it.

  - Syntax fix. @^a is not meta applied to the symbol ^a, but rather meta quasiquote a.



                                     TXR 85
                                   2014-03-07

  Bugs

  - Fixed a regression related to the *random-state* variable, 
    breaking all pseudo-random number functions.

  - Fixed broken "txr -v".



                                     TXR 84
                                   2014-03-07


  Features

  - TXR Lisp no longer uses one quote for regular quote and quasiquote syntax.
    The quasiquote character is now ^ and the apostrophe is just regular quote.
    This change breaks backward compatibility, unfortunately, but the
    single-quote experiment had to come to an end, now that TXR has a powerful
    macro facility, with quasiquotes playing a central role.

  - TXR Lisp exposes the environment manipulation functions make-env, env-vbind
    and env-fbind.

  - New function log10 for base 10 logarithms.

  - New functions open-files and open-files* for opening a big catenated stream
    which marches through multiple files as if they were one.

  - New directive, @(assert), for writing certain kind of robust matching code
    more simply.

  - put-line can be called with no arguments, in which case it just writes
    a newline to standard output.

  - In the format function, if a precision is specified as *, it can now
    have a leading 0 in front of it, which applies as usual (to the formatting
    of an integer which falls short of the number of digits required
    by the precision).

  Bugs

  - In the format function, the * character for specifying a variable
    field width or precision (derived from an integer argument) was broken.

  - Fixed a regression causing the exception "t is not a cons" on queries
    that match data, when no input files are specified.

  - Fixed a regression causing file names not to be tracked in the pattern
    matching language, and consequently error messages not to give that
    useful information.

  - Fixed some bugs related to command line processing, which had recently
    been rewritten: the element nil was being added to *args* in some situations,
    the argument - would end up repeated twice, and args was being sometimes
    manipulated in such a way that (ldiff *full-args* *args*) wouldn't work,
    due to new conses pushed onto *args* so that it's not a structural
    suffix of *full-args*.



                                     TXR 83
                                   2014-03-02


  Features
  
  - The qquote macro is now in the regular user namespace, while the 
    quasiquoting read syntax uses a different macro based on private symbols.
    So when the read syntax is used, the template can contain the symbols
    qquote, unquote and splice, even though these are the basis for
    a quasiquote macro.

  - Diagnosis of attempt to redefine a special operator as a function or macro.
    Remove the macro when a function of the same name is defined and vice-versa.

  Bugs

  - Fixed bugs in the implementation lexical variable shadowing by symbol
    macros.

  - Fixed incorrect handling of trailing atoms in quasiquote.

  - Redesigned the implementaton of special variables, and how they integrate
    with internal C global variables in the interpreter, in order to fix the
    broken dynamic overriding of the predefined globals.

  - The Lisp-1 style evaluation of the dwim operator or square brackets was not
    resolving over-ridden special variables correctly, using a lookup method
    that saw only the global bindings.

  - Fixed missing integration between catenated stream objects and the
    garbage collector.



                                     TXR 82
                                   2014-02-27


  Features

  - Intuitive behavior in various sequence processing in the library:
    don't try to output a string if the resulting items are not characters,
    and then fail; make a list.

  - All operators that were implemented as special code expanding hacks
    in the TXR Lisp code walker are have been converted to intrinsic
    macros. Only a few bona-fide special forms are subject to minor
    code transformations.

  - New generation macro called "gun". (gun (read-line stream))
    produces a lazy list of lines from a stream. gun, which stands
    for "generate until nil", evaluates the enclosed expression while that
    expression produces non-nil values, and makes a lazy list out of them.

  - New function copy, for copying sequences.

  - Documentation improvements thanks to Roman Mishin. 

  Bugs

  - Regression fix: error thrown on valid floating point constants.

  - Doc bugs: documentation was missing for the delay operator
    and the length function.


                                     TXR 81
                                   2014-02-25


  Features

  - Calls to stream opening functions can omit the mode parameter,
    which defaults to "r".

  - New functions for accessing environment variables from TXR Lisp,
    augmenting the @(next :env) method in TXR pattern language.

  - New variables *args* and *full-args* for accessing the
    partial and full command line.

  - New functions macro-form-p, macroexpand and macroexpand-1.

  - Implemented special variables (dynamic scope). All global variables
    defined with defvar and all the predefined variables are special,
    with the symbols being attributed for special binding similarly
    to Common Lisp.

  - Implemented the macrolet operator for binding local macros.
    The macroexpand and macro-form-p functions work correctly with
    the environment from a macrolet.

  - Implemented symbol macros: global symbol macros via defsymacro,
    and local macros via symacrolet. Local symbol maros are shadowed
    properly by lexical bindings, and are expanded properly in
    situations where they are used as assignment places by the
    set operator, and related operators.

  - Introduced the (. expr) syntax which is equivalent to expr.
    Handy for writing a function argument list that accepts
    only trailing parameters as (lambda (. rest) ...)
    rather than (lambda rest ...).

  - New functions prinl and pprinl, which are like print and pprint,
    but add a newline.

  - Added new Unix filesystem access functions: symlink, link, mkdir,
    readlink, mknod. Also makedev, minor and major.



  Bugs

  - Fixed broken seek-to-end-p boolean parameter in open-tail,
    a regression in TXR 71.

  - Fixed a regression in the debugger, also introduced in TXR 71,
    causing it not to print the data line being processed in a horizontal
    scanning context.

  - Fixed premature opening of data sources in the TXR pattern language.
    Opening files is now delayed until a data consuming directive
    needs to match data. The previous kludgy approach recognized only the
    @(next) directive, and only one occurrence of it.

  - Fixed incorrect square root calculation over bignums. It was
    not computing the last bit of the result and so could be off by
    one.

  - Numerous bugfixes in form expansion, in particular handling of
    variable bindings and function and macro parameter lists.

  - Global macro bindings make a symbol fboundp. Also, symbol-function
    retrieves information about a global macro.

  - Fixed several bugs in quasiquote, including the handling of 
    `(... . ,form) in quasiquote.

  - Fixed get-string-from-stream throwing an inappropriate internal error on
    type mismatch.

  - Fixed the neglect to expand Lisp forms in the argument lists
    of the directives of the pattern matching language.

  - Added the neglected s-ifsock variable, which is part of the Unix
    filesystem interface, corresponding to S_IFSOCK.

  - Fixed some instances of source code line number not propagating
    through code transformations.

  - Fixed numerous formatting issues in the documentation, and omissions.



                                     TXR 80
                                   2014-02-17


  Features

  - TXR now nicely handles null characters in text stream inputs.
    They are internally encoded to the Unicode value U+DC00,
    which will map back to a single null byte on output (that being
    existing behavior).

  - TXR now has Lisp macros: the defmacro operator is implemented,
    with destructuring lambda lists and all.

  - New operators tree-bind and tree-case for pattern binding similar
    to Common Lisp's destructuring. This piggybacks off the defmacro
    infrastructure which we now have.

  - Big improvement in debuggability: the unhandled exception error message now
    gives source code location information.

  - New functions pos, pos-if, posq, posql and posqual for finding item
    positions in sequences.

  - Predicate function is now optional in the some, all and none functions.

  - hash-uni and hash-isec functions take a join-func argument which
    lets you specify how elements from two tables are merged.

  - new hash table functions inhash and hash-update-1.

  - two hashes can now be tested for deep equality using equal.

  Bugs

  - Removed bogus optimization from hash table implementation.

  - Syntactic fix: input like 1.0a no longer parses as a floating-point number
    followed by a symbol, but is diagnosed as an error. Syntax like 123a
    continues to work as before: it denotes one symbol, not 123
    followed by a.

  - Bugfix in type check for "cobj" class objects that would crash if
    given non-heaped values like fixnum integers.

  - Corrected problems in the code walking and expansion of lambda and
    defun forms.

  - Fixed failure to propagate line number info through the abstract syntax
    of string quasiliterals.

  - Doc bugs: missing descriptions of gethash and gensym.



                                     TXR 79
                                   2014-02-11


  Features

  - New functions comb, perm, rcomp and rperm for calculating repeating and
    non-repeating combinations and permuations of sequences (lists, vectors and
    strings).  Hashes are supported by comb function.

  Bugs

  - Hardening of code for handling excessively large vectors.

  - Bugfix in quasistring handling in TXR Lisp.

  - Bugfix in if function (not the if operator).



                                     TXR 78
                                   2014-02-06


  Features

  - vec function for making a vector out of its arguments, to complement
    the existing vector function which makes a vector of a given size.

  - The dot position of function call forms can now apply strings and
    vectors. The same is true of the apply function.

  - The apply function now takes additional optional arguments before the list,
    similarly to Common Lisp's apply.

  - New function: list*.

  - Three-element forms for optional parameters are now supported;
    the variable can be specified, an initialization form used when the
    argument is omitted, and a symbol that is bound to a boolean indicating
    whether or not the argument is present. (Common Lisp style, IOTW).

  - New protocol for optional parameters: the colon symbol : can be
    passed as a value for an optional parameter, which causes that
    parameter to behave as if it were missing.

  - reduce-left and reduce-right can now use nil as the initial object,
    which is an useful and important behavior.

  - strings, vectors, lists and hashes are now generally callable like
    functions, not only in the DWIM operator or DWIM brackets notation.

  Bugs

  - Lexical scope of optional argument default init forms now properly
    restricted.

  - Fixed breakages in do operator.

  - Bugfix in logic for tracking source code file and line number info
    that would cause the info to disappear under garbage collection.

  - Fixed a erroneous exception throws in the mutation operator logic
    which would cause usage errors to turn into internal errors.



                                     TXR 77
                                   2014-01-30


  Features

  - More streamlined parser containing fewer hacks, and fewer obscure
    cases that don't work.

  - @'expr syntax now works as expected in directives for evaluating quoted
    TXR Lisp expressions.

  - In nested uses of the do and op operators in TXR Lisp there is now
    a way to refer to the outer parameters from the inner nestings, using
    compounded meta syntax like (op (op @1 @@1)), where @1 is argument 1
    of the function denoted by the inner op, and @@1 is argument 1 of the
    outer function.  Each additional @ "escapes" out one level of nesting
    of the op syntax.

  - New update and hash-update functions.

  - The interfaces of reduce-left and reduce-right functions has been
    improved, making them easier to use, while mostly retaining backward
    compatibility.

  - New functions remove-path and rename-path for removing and renaming
    filesystem objects.

  - Catenated streams, previously an internal feature, are exposed
    now via the make-catenated-stream function.

  - Scope rule change for expressions that provide default intialization
    for optional arguments. These eexpressions now have the parameters
    in scope, and so now uses like (lambda (x : (y (length x))) ...)
    are possible where y is initialized with (length x) if the argument
    is not supplied. Previously, parameter x would not have been considered 
    to be in scope of the expression (length x).

    

  Bugs

  - Fixed neglected handling of result form in dohash syntax.

  - In the object printer, the handling of syntax like @(sys:var x ...) was
    ignoring any additional ... forms, and rendering as @x.

  - Fixed possible race condition in tail streams, whereby when a file
    rotates, the stream prematurely follows the new file, neglecting
    to read the last piece of material just added to the previous file.



                                     TXR 76
                                   2014-01-23
                                   

  Features

  - New time functions: time-fields-local and time-fields-utc for obtaining
    broken-down time from Epoch seconds.

  - New group-by function for constructing a hash from a list when the
    list elements can be partitioned into equivalence classes tied to keys,
    rather than treated individually.

  - Sweeping changes in TXR List to allow vectors and strings to be manipulated
    in many situations as if they were lists. Functions like car, cdr and
    mapcar work on strings and vectors.

  - New command line options -e and -p for evaluating TXR Lisp expressions
    more conveniently from the command line.

  - The and, or and if special operators are now also provided as functions,
    so they can be indirected upon functionally.

  - New functions conses and conses*, useful for iterating over a list
    similarly to Common Lisp's maplist function.

  - New do operator (unrelated to @(do) directive) similar to op, but 
    geared toward doing imperative things involving special operators.

  Bugs

  - @(require ...) directive was not expanding its forms prior to evaluation.



                                     TXR 75
                                   2014-01-16


  Features
  
  - Two new stream functions: unget-char and unget-byte. Some streams now
    support ungetting a byte or character, which was a glaring omission
    in the API, without which some common scanning tasks are awkward.

  - TXR Lisp functions with optional parameters can now specify expressions
    to give those arguments values when the arguments are missing.

  - New operators in TXR Lisp: append-each and append-each*.

  - Change in the Lisp structure printer. The special structure generated by
    the read syntax @sym and @(...) now prints back in the same syntax,
    rather than as (sys:var sym) and (sys:expr ...).

  Bugs

  - Fix in put-byte function: before invoking the underlying operation,
    it was testing whether the put-char operation exists for the stream,
    rather than the put-byte operation. This would result in a crash if
    the stream supports put-char but not put-byte.
  
  - Mistake in calculating bitmasks for regex character class ranges,
    resulting in incorrect behavior for ranges whose upper range is
    a character code corresponding to the last bit of a word in the
    bitmask array, e.g. [A-\x7f], resulting in failures to match
    32 or more characters in the upper end of the range.

  - Missing documentation filled in for the functions throw, throwf and error.



                                     TXR 74
                                   2014-01-13


  Features

  - Maintenance: builds on Cygwin, MinGW and Mac OS X 10.7.3.

  - New math functions: n-choose-k, n-perm-k, cum-norm-dist.

  - lisp-parse function renamed read; old name is obsolescent.

  - In the TXR pattern language, the @ escape can now evaluate a non-compound
    TXR Lisp expression also. Previously compounds like @(+ 1 1) 
    were supported, but atoms like @foo were not.


  Bugs

  - Small fix in how exponent fields of printed floating point values
    are normalized. Across all platforms, there are now no leading zeros
    after the 'e'.
    


                                     TXR 73
                                   2014-01-08


  Features
  
  - The new lisp-parse function scans TXR Lisp expressions at run-time
    out of strings and streams, which means that TXR can now more easily keep
    persistent, complex data in text files.

  Bugs

  - Fixed signal-handling-related performance issue caused by excessive
    calls to the sigprocmask function.



                                     TXR 72
                                   2013-12-17


  Features

  - Syslog functionality: openlog, closelog, syslog, setlogmask.
    Plus: the *stdlog* stream for logging directly to syslog.

  - Stream properties.

  - logand and logior functions become variadic.

  - Signal handling support. TXR Lisp code can catch POSIX signals.

  - Syntax changes in the area of symbol names. Package prefixes are
    supported now, like foo:bar (symbol bar in package foo).

  Bugs

  - Nonsensical error diagnostics in intern and delete-package, in the
    case when a package doesn't exist.

  - defvar is documented now and behaves more similarly to the Common Lisp
    defvar.
  
  - seek-stream with a zero offset was reporting the current offset instead
    of seeking regardless of the value of the whence argument.

                                   

                                     TXR 71
                                   2013-12-07


  Features

  - New functions countqual, countql, countq and count-if.

  - New regex-parse function: parse regex from a string at run-time.

  - New *stdnull* stream for discarding data.

  - New function: seek-stream for positioning within a stream.

  - New function open-tail for opening a new kind of stream called a tail
    stream. This stream follows rotating log files.

  - New functions for converting a time expressed as individual fields
    into numeric time: make-time, make-time-utc.

  - New function daemon (where supported). Calls the BSD-derived daemon
    function to daemonize the process in one step.

  - New errno function for accessing C errno.

  - Real-time input support in pattern matching language, via "simple"
    lazy text stream line lists which sacrifice accuracy of representation for
    timely delivery.

  Bugs

  - Fixed missing recognition for hexadecimal integers in Vim
    syntax higlighting file txr.vim.

  - Fixed missing check for null handle in stdio back-end of flush-stream.

  - Grammar and spelling in HACKING guide.



                                     TXR 70
                                   2013-11-22


  Features

  - Fixed a nasty bug that affects all versions; I was not able to find
    a revision in git that works right with gcc 4.6.3. Invoking an @(accept) in
    the middle of a @(collect) was found not work at all as documented, and
    this was root-caused to my neglect to use volatile on some local variables.

  - Fixed a more recent regression in the op syntax, caused this October.

  - Fixed an amazing regression introduced in TXR 22, back in November 2009,
    easily reproduced using:
    
       echo ":x" | ./txr -c "@x:@x" -

  - Fixed all unintentional deviations from 1990 ISO C. GCC had
    not been diagnosing them for us due to my neglect to use
    the --pedantic flag.

  - Revamped and up-to-date txr.vim syntax file, for you Vim users.



                                     TXR 69
                                   2013-10-23


  Features

  - Multiple @(output) blocks can now continue on the same output stream, which
    is particularly useful if it is a pipe. 

  Bugs

  - Fixed errors in documentation for the functions time-string-local,
    time-string-utc and expt.



                                     TXR 68
                                   2013-10-07


  Features

  - @(repeat) inside @(output)  supports a :vars parameter, making it possible
    to declare the existence of iteration variables that are otherwise hidden
    within Lisp code.

  Bugs

  - Out-of-sequence numeric parameters can be used in the op operator now, like
    (op foo @2) where @1 is absent.

  - The implicit ". @rest" is now added to op forms only if they do not mention
    @rest or any numeric parameters, to prevent unintentional passing of extra
    parameters.

  - @rest or a numeric param like @1 can now be specified in the dot position
    of the op form, as in (op foo . @rest).



                                     TXR 67
                                   2013-07-13


  Features

  - New functions tok-str and string-cmp.
  
  - Internal lazy string functions exposed as intrinsics.

  - New pattern language directive: @(require ...).

  Bugs

  - Unrecognized backslash escapes in string literals
    and string quasiliterals are diagnosed.

  - Backslash-space escape recognized in string literals
    and string quasiliterals.



                                     TXR 66
                                   2013-05-16


  Features

  - Documentation completely filled in.

  - Added specfile for RPM builds.

  - @(repeat) introduced as shorthand for @(collect :vars nil).

  - New open-command and open-process functions. The open-pipe
    function becomes deprecated.

  - New multi-sort function for sorting two or more lists
    at the same time as if they were columns of a table.

  - assq and aconsq functions are renamed to assql and
    aconsql becuse they use eql equality, not eq.

  - New prop function for property list lookup.

  - New stat function for information about files.

  - New functions in hashing library: 
    - Copying hashes: make-similar-hash, copy-hash 
    - Set operations: hash-uni, hash-diff, hash-isec.

  - Gapingly missing hexadecimal integer constants have been
    implemented.

  - New bit operation functions that work with TXR's arbitrary precision
    integers: loand, logior, loxor, lognot, logtest, ash.

  - Test form in for loop can be omitted.

  - New package-related functions.

  - New functions for obtaining time of day and converting to text.

  Bugs

  - Fixed broken (+ <fixnum> <char>) case in addition.
    This fixes the range and range* functions too.

  - Fixed nonworking building in a separate directory.

  - Fixed broken eval function.

  - Bugfix in form expander's handling of regular expression
    syntax, causing the (set ...) notation for character
    sets being mistaken for the (set ...) assignment operator.
  
  - Bugfix in format: apply field formatting to argument
    not only if a nonzero with has been specified, but also
    if a precision has been specified.

  - Bugfix in format: ~s on a floating point number now
    always shows .0 except when a precision is given,
    and it is zero.

  - Fixed broken @(last) clause processing of @(collect),
    int he case when the last material matches at the end of a stream.

  - Fixed certain function applications not being able to
    call functions that have optional arguments with
    fewer than 



                                     TXR 65
                                   2012-04-20


  Features

  - New ways to iterate over hash tables using lazy lists.

  - Regular expression compiler expressed to user code, allowing TXR
    programs to build regex abstract syntax trees and turn them into
    regular expression machines.

  - The popular regular expression tokens \s, \d, \w and \S, \D, \W are now
    supported (the first three of these in character classes also).

  - Low level time-of-day functions added for retrieving epoch seconds,
    and optionally microseconds.

  - New remove-if and keep-if functions, plus lazy counterparts
    remove-if* and keep-if*.

  - Lazy variants remq*, remql* and remqual* added.

  - New function find-if.

  - Improved seeding of pseudo-random-number generator.

  - Configure script now diagnoses specification of nonexistent config
    variables.

  - Documentation improvements.

  - Portability to Mac OS/X 10.7 (Lion), NetBSD 5.1 and FreeBSD 9.0.

  Bugs

  - Bugfix in @(next) directive, which showed up when using @(next :args)
    more than once to scan arguments more than once.

  Quiet Changes

  - First two arguments to the find function were reversed.



                                     TXR 64
                                   2012-04-06


  Features

  - In the pattern language, binding the symbol nil as a variable
    is permitted now and has a special meaning of matching and
    discarding input.

  - Caching optimization in hash tables.

  - Ephemeral GC implemented. This is experimental and currently
    must be enabled at compile time with the --gen-gc configure
    option.

  Bugs

  - Interaction between @(trailer) and @(accept) has been clarified.
    An @(accept) return from the forms of a @(trailer) will still
    roll back the input position to the starting point for the
    @(trailer).





                                     TXR 63
                                   2012-03-30


  Features

  - Significant improvement in the performance of the garbage collector,
    which can drastically cut the run-time of some programs.
  - match-str and match-str-tree functions exposed.
  - new @(rebind) directive provides for a one step dynamic shadowing
    of a variable with a local variable, whose value can be derived from
    the one being shadowed.
  - filters now work on nested lists of strings, not just strings.
  - floating point formatting now produces the same exponential notation
    on different platforms, by post-filtering the sprintf output:
    a leading + and leading zeros are removed: e+023 becomes e23.
  - new functions: num-str, tan, asin, acos, =, 
  - min and max return the left operand rather than the right one,
    when two operands are equal.


  Bugs

  - search-str optional argument was not working when omitted.
  - Fixed situations involving an incorrect behavior: partial horizontal
    matches (not matching the full line) were succeeding.
  - It was impossible to define a pattern function called @(text)
    due to the use of the symbol text as an internal symbol, rather
    than a symbol in the private system package.
  - error checking code in funcall had an improperly terminated argument
    list, causing an exception.
  - @(output) blocks now flush their stream at the @(end), without
    which output is not correctly interleaved between output produced
    by external commands.
  - fixed some misleading exception wordings in the numeric library.
  - fixed sign semantics of floating-point mod to be like the integer mod.
  - gcd function allows zeros.
  - fixed broken exptmod: it was not normalizing bignum values that
    fall into the fixnum range into fixnum objects, resulting in 
    undersized bignums being returned.



                                     TXR 62
                                   2012-03-23


  Features

  - Floating-point support has been added. 
    - TXR programs can specify floating-point constants. 
    - Printing floting points is supported in the format function.
      - New specifiers: ~f and ~e.
    - Arithmetic on floating points, with implicit
      conversion. 
    - New / function which produces a floating-point result.
    - New functions like sin, cos, exp, and log.
    - Functions for converting between floating and integer,
      and parsing a float from a string.

  - New combinators for easier programming with higher order functions: chain,
    andf, orf, iff.

  - url_decode and url_encode functions take an optional parameter which
    determines whether + is used as the code for space, distinguishing
    URL encoding from percent encoding. Separate named filters are
    introduced: :frompercent, :topercent distinct from :fromurl and :tourl.

  Bugs

  - Buggy quicksort routine repaired. This is a recently
    added feature which allows vectors and strings to be sorted. 
    List sorting, done by merge sort, is unaffected.

  - Breakpoints can now be set by line number and file name, allowing
    breakpoints in loaded modules, not just the main module.

 
  
                                     TXR 61
                                   2012-03-15


  Features

  - URL encoding and decoding functions added, and :tourl/:fromurl
    filters implemented for output substitution.

  - split-str function works with regex objects now.

  - new regsub function for regex substitution in strings;
    matched text can be filtered through a function.

  - new *stddebug* stream used by debugger.

  - put-byte works on string output streams, and does right
    thing with mixtures of bytes (which are taken as UTF-8)
    and characters written with put-char.

  - Hash table literals implemented; hashes can now be notated
    rather than constructed.

  - Vectors can now be quasiquoted with unquote and splicing,
    and so can the new hash table literals.

  - @(block) syntax change: blocks do not extend to the end of
    the surrounding scope but introduce their own, delimited
    by @(end).

  Fixes

  - Fixed memory leak in string byte input stream.

  - Fixed wrong parsing of tokens in cases like @(collect-foo)
    where this was treated as @(collect -foo) rather than a single token.
  


                                     TXR 60
                                   2012-03-04


  Features

  - List element removing functions: remq, remql, remqual.

  - Memory use optimizations in @(freeform) horizontal scanning.

  - Improved hashing function for bignums.

  Bugs

  - Fixed incorrect processing within long lines, caused by
    earlier optimizations in 57.

  - Missing 'd' command for deleting a breakpoint implemented
    in the debugger.

  - numberp function no longer blows up on nil.

  - Fixed broken @(load) directive: was not allowing directives
    which follow it to be processed.

  - Fixed incorrectly formatted line number information in
    some exceptions.

  - Fixed missing support for optional and trailing parameters
    in defun.

  - Fixed showstopper bug in plus function.



                                     TXR 59
                                   2012-02-29


  Features

  - Implemented put-byte function on streams.

  - Regex syntax in TXR Lisp changes from /re/ to #/re/, allowing
    symbols containing slashes.

  - New -B command line option forces TXR to dump the bindings even
    if the program produced output.

  - Revised and improved txr.vim syntax highlighting file for greater
    lexical accuracy and superior flagging of errors.

  Fixes

  - Regression that broke [n..t] and [n..nil] sequence ranges.

  - Broken hex-escaped character literals.

  - Old bug from database: filter functions now see bindings in all
    contexts in which they are invoked.

  - Output clauses consisting of one empty line were being treated as empty.

  - Implemented more sane rule for deciding when output has taken place
    and suppress the printing fo bindings.



                                     TXR 58
                                   2012-02-25


  Features

  - Exception handling exposed in TXR Lisp.

  - range* function similar to range, but for generating a range with the
    endpoint excluded.

  - TXR Lisp can invoke a function in the pattern language now using
    the new match-fun function.

  - Braced variable syntax in @(output) extended to support arbitrary
    expressions in place of the variable name. The expressions are converted
    to text and then treated the same way as a variable substitution.
    Indexing is allowed, and field-formatting takes place.
    Moreover, these expressions are code-walked by @(repeat) and @(rep) to look
    for embedded variables.

  - New TXR Lisp functions ref, refset, sub and replace.

  - Indexing and range extraction in brace substitution in @(output) clauses is
    now generic over lists, vectors and strings.

  - Optional arguments introduced into TXR Lisp, in defun and lambdas,
    with a simple syntax involving a colon. Numerous intrinsic functions
    have been converted such that some previously required arguments
    are now optional.

  - Sort function that was previously for lists only is now generic over
    vectors and strings.

  - New del operator in TXR Lisp can delete elements of sequences or hashes
    which are denoted using the bracket syntax.

  - Range indexing has "floating zero" behavior now so that for
    example [seq -2 0] means the "last two elements": when the start of
    the range is negative, then a zero end is treated as length plus one.

  - TXR programs can now be split into multiple modules, using the load
    directive to load and run code.

  Bugs
  
  - range function terminates lazy list when the sequence overshoots
    the final value.

  - Variable that holds nil is treated as a list in (set [var x..y] ...)
    range assignment.

  - Vestigial (t . obj) representation in exception handling code removed.

  - TXR now does not not dump bindings if any output occured on a stream
    connected to the C stdout stream. Previously, it suppressed printing
    of bindings if @(output) was carried out on the *std-output* stream.

  - Function remhash was found to be buggy and rewritten.



                                     TXR 57
                                   2012-02-14


  Features

  - Operations under the @(freeform) directive can now scan in constant memory,
    allowing large files to be processed.  (Scanning a single regex still
    requires the data to be all in memory: an experimental patch for this
    exists.)

  - Improved printing of character position context in debugger when lines are
    long.

  - Metanums (@1, etc) can be used in a quasiliteral, which is useful for
    quasiliterals occuring inside the op notation.

  Bugs

  - lazy-flatten function did not handle atoms. This broke @(next :list expr)
    also, for the case where expr evaluates to a string atom.

  - In format, the ~s directive was found to be printing strings in the same
    way as ~a.

  - Hex and octal character constants did not work.

  - Control characters in strings and characters are printed as hex now rather
    than octal. A semicolon is added if the next character would be interpreted
    as part of the escape.

  - Hash indexing via the [] notation was still requiring the default value
    argument.



                                     TXR 56
                                   2012-02-06


  Features

  - Hex and octal escapes work in strings and quasilterals now: the
    documentation has stopped lying. 
    - Escapes can be followed by a semicolon which terminates them and is
      removed, which is useful if an escape is followed by characters
      that would otherwise be interpreted as part of the escape.

  - More color categories and more accurate syntax in Vim syntax
    highlighting file. Highlights @[...] syntax properly inside quasiquote.

  - The third argument (the default value if a key is not found) can be omitted
    when indexing hashes with the [hash key] syntax. It defaults to nil.

  - The dwim operator (and thus [] syntax) is even more Lisp-1 like. It
    now has Lisp-1 namespace semantics for evaluating arguments
    that are symbols.

  - A new operator called "op" as been added. This allows simple lambda
    functions to be written as partial evaluatios of functions, with implicit
    arguments as well as numbered/rest arguments appearing in the body.


  Bugs

  - Fixed missing type check in hash module that allows bad code
    to crash interpreter instead of getting an excepion.

  - Fixed regression in TXR 55 which broke computed field widths in output
    variables.

  - Fixed incorrect UTF-8 decoding of some code points.

  - Closed several security holes in UTF-8 decoder by recognizing all invalid
    UTF-8 sequences, and mapping invalid bytes in such a way that any byte
    sequence processed by the decoder into Unicode code points will be
    recovered exactly when encoded back into UTF-8.



                                     TXR 55
                                   2012-01-26


  Features

  - New square bracket syntax for Lisp-1 like invocation
    and array-indexing over lists, vectors, strings and hashes.

  - New a .. b pair syntactic sugar for (cons a b).
    Works with array indexing brackets to extract ranges
    (slices) from lists, vectors and strings.

  - Indexed elements and slices are assignable.

  - In the pattern language, variables in output templates (output variables)
    can be indexed and sliced.
  
  - Output variables that hold lists are now interpolated with spaces
    between, and this can be overridden with any separator string.



                                     TXR 54
                                   2012-01-21


  Features

  - Improved debugger: 
    - step into
    - step over
    - finish
    - backtrace for pattern and TXR Lisp functions.
    - dump more complete environment. 

  - Debugging support can be disabled at compile time: configure
    with --no-debug-support.

  - New lazy append function (append*).



                                     TXR 53
                                   2012-01-11


  Features

  - In variable substitutions in output and quasiliterals, the field
    width expression is now evaluated.

  - TXR Lisp:

    - New operators and functions for generating lazy lists more conveniently. 
    - lazy mapcar and mappend: return lazy list.
    - delay and force operators.
    - parallel iteration/collection over lists.
    - list-str function for splitting string into list of characters.

  Bugs

  - Fixed global buitin variables, broken in 52. Properly implemented
    intended fix.



                                     TXR 52
                                   2012-01-07


  Features

  - @(rep) and @(repeat) now take an keyword argument, :counter.
    This specifies the name of a variable which holds the repetition
    count, thus making the count available within the repeated body.

  - New @(mod) and @(modlast) clauses in repeat/rep, allowing special
    behaviors to be coded based on whether the repetition count is
    a particular value modulo some number.

  - @(gather) directive now supports an @(until)/@(last) clause,
    so the search range can be restricted.

  - New directive @(fuzz) for doing an imprecise match over a range
    of lines, similar to the context line fuzz logic in the patch utility.

  - gensym function added to TXR Lisp, along with a *gensym-counter*
    global variable.

  Bugs

  - Fixed a regression in repeat/rep triggered when multiple clauses of the
    same type appear (like two occurences of @(last)).

  - Built-in global variables in TXR Lisp now properly denote the
    underlying C variable locations, rather than holding copies of the values
    of those variables.  If you assign to *stdout*, it will now really replace
    the stdout stream stored in the corresponding C variable (std_output), so
    it has the proper global effect. Previously, this action would just
    replace *stdout* with a new value, without any effect on std_output.



                                     TXR 51
                                   2011-12-28


  Features
  
  - Better algorithm in the random function for generating evenly-distributed
    pseudo-random numbers of arbitrary precision.

  - PRNG startup behavior improved.

  - New lazy-flatten function for flattening lists lazily. Used within
    @(next :list ...) implementation, making it possible to scan through
    Lisp-generated lazy lists.

  Bugs

  - Fixed showstopper bug introduced in a patch for the MPI library,
    affecting 32 bit platforms.

  - Fixed bug in Lisp expression interpolation in quasiliterals.

  - Fixed fatal exception being thrown in verbose mode, by one of
    the formatted print statements.



                                     TXR 50
                                   2011-12-23


  Features
  
  - Dropped silly leading 0 from version number. :)

  - New vector functions: copy-vec, sub-vec, cat-vec.

  - New API for pseudo-random-number generation, complete with
    independent random state objects that can be seeded and copied.

  - Vim syntax highlighting definition improvements.

  - In the format function, left-adjustment is specified using <
    rathr than the - character. (However a negative width specified
    as an argument using * still means left adjust.)  The leading
    zero for zero padding as well as the sign character (space or +)
    are specified in the precision field, not the width field.

  - More complete documentation.

  - Slight return value convention change in some and all functions.

  - Added memql function.

  Bugs

  - Critical flaw in hashing fixed that could crash on some platforms.

  - Exception handling fix: if a catch clause performs a
    non-local exit, the finally clause is still executed.

  - "make distclean" fixed.

  - Fix for differences in syntax error diagnosis between Byacc and Bison.

  - Fixed a memory leak in a division-by-zero case in the bignum mod
    function.

  - Fixed a terrible bug in one of the MPI patches affecting the correctness
    of various operations on numbers having a 1 in the most significant
    bit position of the most significant digit word.

  - Fixes in format function. All objects obey field width and left/right
    alignment. Numeric precision, zero padding and optional sign all works.

  - Lisp code evaluated in @(repeat)/@(rep) clauses can now see all variables,
    not just the ones subject to the repeat. (But whether or not a repeat
    executes, or which clauses, is still independent of what variables
    are accessed by the embedded Lisp, taking into account only the variables
    directly embedded in the clause.)



                                    TXR 049
                                   2011-12-19


  Features

  - New functions for converting between characters and integers.

  - Some arithmetic and relational operations are generic over characters in a
    way that makes sense.

  - dohash establishes anonymous block.

  - Improvements in Vim syntax highlighting file.

  - Lazy cons semantics cleaned up making lazy list programming easier.

  - Some API renaming and restructuring in the area of vectors.

  - Semicolon comments supported in Lisp code and @; comments in the pattern
    matching language. @# becoming obsolescent.

  - Not function, synonym for null.
  
  - Some progress in TXR Lisp documentation.

  - Hashing functions improved for fixnums, literals and characters.

  - API for introspecting over interpreted functions added, in anticipation
    of doing some compiler work.

  - Quasiliteral strings supported in TXR Lisp.

  Bugs

  - Broken abs function fixed for bignums.

  - mappend semantics clarified and fixed: behaves like append for
    improper lists and atoms.
 
  - Bugfix in code walker for let/let* forms, which resulted in quasiquotes
    not being expanded.

  - Fixed incorrect format arguments in some error messages, resulting
    in aborts in some error cases, instead of the intended diagnostics.



                                    TXR 048
                                   2011-12-13


  Features

  - New functions: expt, exptmod, sqrt, numberp, evenp, oddp, abs, gcd
    reduce-left, reduce-right.

  - Replaced horribly slow square root in MPI with a less horribly slow one.

  Bugs

  - Fixed numerous instances, in the MPI library, of coding broken
    for mpi_digit wider than 16 bits, leading to incorrect results and
    crashes.

  - Fixed mpi_int for 32 bit platforms so that obj_t stays 4 pointers wide.
    (The sign becomes a 1 bit wide bitfield).



                                    TXR 047
                                   2011-12-12


  Features

  - Transparent bignum arithmetic: when operations on machine word (fixnum)
    integers overflow, multi-precision (bignum) integers are produced.

  - TXR Lisp:

    - New operators: progn, flip.
    - Vector functions added, and vecref is an assignment place.
    - Character manipulation functions.
    - Association list functions.
    - Implicit anonymous block around forms for loop.
    - Implicit named block around forms for loop.
    - Nump renamed to fixnump.
    - Push arguments reversed: (push obj list).

  - Syntax highlighting definition update for all new operators.

  Bugs
  
  - Another bugfix to character literals, allowing non-alphanumeric
    constants like #\$.

  - Fix in rplacd to make lazy list programming feasible.

  - Reversed assoc and assq arguments throughout codebase.

  - Debugger: repeating last command by pressing Enter works again.



                                    TXR 046
                                   2011-12-06


  Features
  
  - Vector-related functions exposed in Lisp interpreter.

  - Syntax added for specifying vector literals in code.

  - Length function made generic over strings, lists and vectors.

  Bugs

  - Broken get_line function over string input streams fixed.

  - Some kinds of character literals were not being recognized properly.

  - bugfixes in configure script, affecting 64 bit Mac OS X. Thanks
    to Andy Wildenberg for reporting issue and confirming root cause.



                                    TXR 045
                                   2011-12-05


  Features
  
  - New functions exposed in Lisp interpreter: strings, characters,
    symbols and lazy lists.

  Bugs

  - Flaws in some string-splitting functions identified and fixed.

  - Bugs in quasiquote.

  - Handling of singleton clauses in cond operator.



                                    TXR 044
                                   2011-12-01


  Features

  - Lisp interpreter added.

  - Relaxed rules for what constitutes symbol names.


  Bugs

  - Regression in source location tracking (line numbers
    shown in debugger and trace output).

  - Regression in vertical skip directive caused it to ignore
    its arguments.

  - Fixed :vars () in collect/coll not working as intended.
    This should prevent any bindings from being collected, and
    allows iteration with collect without accumulating memory.

  - Two-year-old bug in weak hash tables.




                                    TXR 043
                                   2011-11-23


  Bugs

  - Buggy @(eol) directive fixed.

  - Semantics change for text and regular expressions in "negative match":
    - a variable is considered to be followed by a run of text which
      consists of any mixture of regexes and literal text
    - thus @foo bar behaves properly once again; it is not treated
      as foo followed by the regex / +/, ignoring the text bar.

  - Infinite looping bug in negative match with longest-match semantics.

  - Bug in the overflow detection in the lib.c plus and minus function.




                                    TXR 042
                                   2011-11-20


  Features

  - Access to environment via @(next :env)
  - New @(gather) directive for matching out-of-order material.

  - Horizontal functions:
    - TXR can now parse grammars.
    - Variable syntax allows capture of text spanned by function calls:
      e.g. @{var (func x y)}: text spanned by (func x y) goes into var.

  - Horizontal modes for numerous directives such as @(bind), @(local), ...

  - Lisp-style bindings output.

  - Interactive breakpoint/step debugger added.
    This is an experimental prototype, but already quite useful.

  - Directives following a variable match have searching semantics now,
    as do function calls. @a@(foo) will scan for a match for @(foo),
    and the text skipped over is captured by a.

  - New :resolve keyword in @(some) directive allowing conflicting
    variable bindings to be set in separate clauses and resolved.

  - deffilter is more powerful: arguments are evaluated so filters can
    be computed by the query.

  Bugs

  - Horizontal @(some) directive hooked in.

  - @(freeform) with no data fails to match instead of throwing strange error.

  - Setting non-local variables from a function works now.

  - Stability fix: several long-time uninitialized variable bugs found,
    and some faulty object initialization orders.

  - :vars in @(collect)/@(coll) does not fire an exception about missing
    required variables if no variable bindings are produced at all,
    allowing strict collects to have explicit matches for unwanted material
    without triggering this nuisance error.

  - @(repeat)/@(rep) allow empty body.

  Internal

  - New infrastructure for matching location info to source forms.
    Location info (currently just the line number) is associated with
    source forms via a weak hash table.

  - Character literals are now Lispy (hash-backslash syntax), based on Scheme.

  - Added quote, unquote and splicing syntax similar to Lisp. Not used
    for anything yet.

  - Improved Valgrind integration: more accurate, timely detection of
    uninitialized fields in heap objects.

  Misc.

  - A TXR syntax highlighting file for the Vim editor exists
    now. See the txr.vim file.




                                    TXR 041
                                   2011-10-30


  Features

  - New :append keyword in @(output) to append instead of overwriting.

  - Variable contents can be treated as input sources using :string
    and :list keywords in @(next). Variables can be treated as output
    destinations using :into keyword in @(output).

  - New @(set) directive for destructive assignment to a variable.

  - New filters: :upcase and :downcase.

  - @(bind) can now compare left and right objects through filters.

  - Filters can now be chained into compound filters.

  - Pattern matching functions can be used as filters.

  - Shorthand notation in @(deffilter) when multiple strings map to the
    same replacement string.

  - @(cat) directive changes syntax.

  - Error handling improvements in parser: no more reams and reams of
    errors.


  Bugs

  - Runaway recursion in @(block) directive, introduced in 040.

  - Fixed bug in matching list variable against text, at the same
    time clarifying semantics to longest-match.

  - Fixed potential excessive memory use caused by refactoring in 040.