use hof

Higher-Order Function combinators. Combinators are functions that combine or apply other functions in useful patterns. They enable functional programming without explicit temporary variables.

Functions

fn all

Check if all elements satisfy a predicate.

Signature: (arr:[]i64 pred:fn(i64 -- i64)

Example:

arr fn (x:i64 -- r:i64) { 0 > } hof::all  // all positive?

fn any

Check if any element satisfies a predicate.

Signature: (arr:[]i64 pred:fn(i64 -- i64)

Example:

arr fn (x:i64 -- r:i64) { 0 > } hof::any  // any positive?

fn apply

Apply a function to a value.

Signature: (x:i64 f:fn(i64 -- i64)

Example:

5 fn (x:i64 -- r:i64) { 2 * } hof::apply print nl  // 10

fn bi_star

Apply two functions to two values (first to first, second to second).

Signature: (x:i64 y:i64 f:fn(i64 -- i64)

Example:

3 4 fn (x:i64 -- r:i64) { 1 + } fn (x:i64 -- r:i64) { 2 * } hof::bi_star  // Stack: 4 8

fn bi

Apply two functions to the same value.

Signature: (x:i64 f:fn(i64 -- i64)

Example:

5 fn (x:i64 -- r:i64) { 2 * } fn (x:i64 -- r:i64) { 3 + } hof::bi  // Stack: 10 8

fn both

Apply a function to two values separately.

Signature: (x:i64 y:i64 f:fn(i64 -- i64)

Example:

3 4 fn (x:i64 -- r:i64) { dup * } hof::both  // Stack: 9 16

fn dip

Apply a function to the second stack element, preserving the top.

Signature: (x:i64 y:i64 f:fn(i64 -- i64)

Example:

10 20 fn (x:i64 -- r:i64) { 2 * } hof::dip  // Stack: 20 20

fn filter

Filter an array, keeping only elements that satisfy a predicate.

Signature: (arr:[]i64 pred:fn(i64 -- i64)

Example:

arr fn (x:i64 -- r:i64) { 2 mod 0 == } hof::filter  // keep evens

fn find

Find the first element satisfying a predicate.

Signature: (arr:[]i64 pred:fn(i64 -- i64)

Example:

arr fn (x:i64 -- r:i64) { 10 > } hof::find  // first > 10

fn fold

Fold/reduce an array left-to-right with a binary function.

Signature: (arr:[]i64 acc:i64 f:fn(i64 i64 -- i64)

Example:

arr 0 fn (acc:i64 x:i64 -- r:i64) { + } hof::fold  // sum of array

fn fold_right

Fold/reduce an array right-to-left with a binary function.

Signature: (arr:[]i64 acc:i64 f:fn(i64 i64 -- i64)

Example:

arr 0 fn (x:i64 acc:i64 -- r:i64) { + } hof::fold_right  // sum of array

fn keep

Apply a function but keep the original value.

Signature: (x:i64 f:fn(i64 -- i64)

Example:

5 fn (x:i64 -- r:i64) { 2 * } hof::keep  // Stack: 10 5

fn map

Map a function over an array, returning a new array.

Signature: (arr:[]i64 f:fn(i64 -- i64)

Example:

arr fn (x:i64 -- r:i64) { 2 * } hof::map  // double each element

fn times

Apply function n times to an initial value.

Signature: (x:i64 n:i64 f:fn(i64 -- i64)

Example:

2 4 fn (x:i64 -- r:i64) { dup * } hof::times print nl  // 65536 (2^16)

fn tri

Apply three functions to the same value.

Signature: (x:i64 f:fn(i64 -- i64)

Example:

5 fn (x:i64 -- r:i64) { 1 + } fn (x:i64 -- r:i64) { 2 * } fn (x:i64 -- r:i64) { dup * } hof::tri  // Stack: 6 10 25

fn unless

Apply function only if condition is false, otherwise return value unchanged.

Signature: (x:i64 cond:i64 f:fn(i64 -- i64)

Example:

5 0 fn (x:i64 -- r:i64) { 2 * } hof::unless print nl  // 10
5 1 fn (x:i64 -- r:i64) { 2 * } hof::unless print nl  // 5

fn when

Apply function only if condition is true, otherwise return value unchanged.

Signature: (x:i64 cond:i64 f:fn(i64 -- i64)

Example:

5 1 fn (x:i64 -- r:i64) { 2 * } hof::when print nl  // 10
5 0 fn (x:i64 -- r:i64) { 2 * } hof::when print nl  // 5