SxScript

Embeddable scripting language for C# written in C#.

Install-Package SxScript

Hello world:

SxScript.SxScript script = new SxScript.SxScript();
string stdout = await script.Interpret("print \"hello world\"");

First 10 Fibonacci numbers, recursive:

function fib(n) {
  if (n <= 1) return n;
  return fib(n - 2) + fib(n - 1);
}

for (var i = 0; i < 10; i++) {
  print fib(i);
}

// result: 0 1 1 2 3 5 8 13 21 34

Check https://github.com/lofcz/sxscript/tree/master/SxScriptTests/Programs for more programs.

Goals of this project are (in order of priority, desc)

• good test coverage
• support both adhoc evaluation and il bytecode + vm
• high IO throughput via async/await
• safe by default, require explicit whitelisting of CLR interop
• allow limitation of execution time, memory used, intructions executed, recursion depth, enumerables length, iterations in looping statements
• syntactically be a relaxed subset of C# (inclined towards Lua, JS)
• visitable AST

Progress tracker

• statements
  • branching
    • if
    • else if / else
    • ternary (a ? b : c)
    • switch
  • looping
    • while
    • for
    • foreach
  • jump
    • goto
    • break
    • continue
    • return
  • labeled
  • label
  • case
  • default
  • scope
  • code block {}
  • global scope
  • variable shadowing
  • logical
  • and / &&
  • or / ||
  • short circuit
  • bitwise
  • &
  • |
  • modifiers
  • await
  • async
  • public
  • private
  • static
  • base types
  • function
  • null / nill
  • int
  • double
  • string
  • bool
  • object
  • true, false
  • array (hashmap)
• operators
• assignment
• unary +, -
• binary +, -, *, /, %, ^
• compound assignment +=, *=, /=, -=, %=, ^=
• null coalescing ??, ??=
• postfix
• ++, --
• arrays
• object members
• comments
• // single line
• /* */ multiline comment. nesting won't be allowed
• evaluation
• interpretation
• bytecode + vm
• OOP
• classes
• this
• constructors
• static methods
• access modifiers (public, private)
• inheritance
• polymorphism
• getters & setters
• traits
• FFI
• (partially) calling FFI functions, this should support both Func<T1..T16> + Action<T1..T16> and Func<Task<T1..T16>> + Action<Task<T1..T16>>
• sugar
• default parameter values fn sum(a = 1, b = 2) {}
• parameter by name myFn(myParam: 1)
• misc
• local functions
• anonymous functions (lambdas)
• params fn sum(params numbers)

Notes

• semicolons are optional
• parenthesis around keywords are optional. Both if (condition) and if condition are valid
• scopes are optional. Implicit scope is one statement. a = 0 if 1 > 2 a = 2 print a is valid
• tabs are always discarded (no ident / dedent)
• newlines are almost always discarded
• dynamic type control. Optional static types. Implicit var declaration. Both a = 0 and var a = 0 is valid. In future int a = 0 should be valid too.
• SxScript is as permissive as possible. Aborting execution is always considered the last option. This is probably not a very good design but I love languages with this behavior (Lua).
• exceptions are not used to control flow (return, continue, break..)

Great projects I'd like to mention here

• https://github.com/codingseb/ExpressionEvaluator
• https://github.com/moonsharp-devs/moonsharp/
• https://github.com/scriban/scriban
• https://github.com/sebastienros/fluid
• https://github.com/sebastienros/jint
• https://github.com/microsoft/ClearScript
• https://github.com/munificent/craftinginterpreters (literature)