hof

Higher-order function combinators for Quadrate.

Installation

quadpm install https://github.com/quadrate-language/hof

Usage

use hof

fn main() {
    // Apply a function to a value
    5 fn (x:i64 -- r:i64) { 2 * } hof::apply print nl  // 10

    // Apply two functions to the same value
    5 fn (x:i64 -- r:i64) { 2 * } fn (x:i64 -- r:i64) { 3 + } hof::bi
    print nl print nl  // 10 8

    // Apply but keep original value
    5 fn (x:i64 -- r:i64) { 2 * } hof::keep
    print nl print nl  // 10 5
}

Functions

Basic Combinators

Function	Signature	Description
apply	( x f -- r )	Apply function f to x
bi	( x f g -- a b )	Apply f and g to same x
tri	( x f g h -- a b c )	Apply f, g, h to same x
keep	( x f -- r x )	Apply f, keep original x
dip	( x y f -- r y )	Apply f to x, preserve y
both	( x y f -- a b )	Apply f to both x and y
bi_star	( x y f g -- a b )	Apply f to x, g to y

Conditional Combinators

Function	Signature	Description
when	( x cond f -- r )	Apply f if cond is true
unless	( x cond f -- r )	Apply f if cond is false
times	( x n f -- r )	Apply f n times

Function Composition

Function	Signature	Description
compose	( f g -- fg )	Compose two functions: fg(x) = g(f(x))
curry	( x f -- curried )	Fix first argument of binary function
curry_right	( y f -- curried )	Fix second argument of binary function

Array Operations

Function	Signature	Description
fold	( arr count init f -- result )	Left fold/reduce
fold_right	( arr count init f -- result )	Right fold/reduce
map	( arr count f -- result count )	Map function over array
filter	( arr count pred -- result count )	Keep elements matching predicate
any	( arr count pred -- bool )	Check if any element matches
all	( arr count pred -- bool )	Check if all elements match
find	( arr count pred -- elem found )	Find first matching element

Examples

Compose functions

use hof

fn main() {
    // Create a composed function: double then add 1
    fn (x:i64 -- r:i64) { 2 * }
    fn (x:i64 -- r:i64) { 1 + }
    hof::compose -> f

    5 f call print nl  // 11 (5*2 + 1)
}

Curry a binary function

use hof

fn main() {
    // Create add5 from generic add
    5 fn (x:i64 y:i64 -- r:i64) { + } hof::curry -> add5

    10 add5 call print nl  // 15
    20 add5 call print nl  // 25
}

Fold an array

use hof

fn main() {
    // Sum array elements
    5 make<i64> -> arr
    arr 1 append -> arr
    arr 2 append -> arr
    arr 3 append -> arr
    arr 4 append -> arr
    arr 5 append -> arr

    arr 5 0 fn (acc:i64 x:i64 -- r:i64) { + } hof::fold
    print nl  // 15
}

License

Apache-2.0 - See LICENSE for details.

Contributing

Contributions welcome! Please open an issue or submit a pull request on GitHub.