data.function ≡

Identity function.

prop> id(x) == x

Return a generic closure which ignores its argument and always returns x

>>> apply(constant(false), 10)
false

Function composition

Composition with a binary function

>>> zip_with(compose2(reinterpret_cast<uint32>, f32::mul), {1.2, 3.0}, {9.0, 4.3})
{0xCD, 0x67}

Apply one argument to a curried function

Curry a binary function

A curried function is a function that takes one argument at a time.

For example, a curried binary functions is a unary function that returns a unary function. Curried functions can be applied using apply or converted into uncurried functions using uncurry.

prop> apply(apply(curry(add), 1), 2) == add(1, 2)

Convert a curried function into uncurried unary function

Convert a curried function into uncurried binary function

Convert a curried function into uncurried three parameter function

Bind a value to the function argument

Bind a value to the first argument of a function

>>> apply(bind1st(sub, 6), 3)
3

Apply a function to the first argument

Bind a value to the second argument of a function

>>> apply(bind2nd(sub, 2), 6)
4

Apply a function to the second argument

Return true if the unary predicate is false

>>> apply(not(is_valid), make_optional(true, 10))
false

Return true if the binary predicate is false

>>> zip_with(not2(less_than), {1, 2}, {3, 1});
{false, true}

Select one of two arguments using the binary predicate

>>> reduce(selecting(less_then), {1, 4, 0});
0

Flip function parameters

>>> zip_with(flip(less_than), {1, 2}, {3, 1});
{false, true}

Compose the function N times.

>>> apply(compose_endo<3>(increment), 1)
4

>>> apply(compose_endo<3>(compose_endo<2>(increment)), 1)
7