gextra/pair

map

pub fn map(pair: #(a, a), map: fn(a) -> b) -> #(b, b)

Applies the given function to both elements of the pair.

let p = #(1, 2)
let assert pair.map(p, fn(x) { x * 2 }) = #(2, 4)

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pub fn new1(first: a) -> #(a, Nil)

Creates a pair with the given value as the first element and Nil as the second.

let assert pair.new1(1) = #(1, Nil)

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pub fn new2(second: a) -> #(Nil, a)

Creates a pair with Nil as the first element and the given value as the second.

let assert pair.new2(1) = #(Nil, 1)

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pub fn replace_first(pair: #(a, b), first: c) -> #(c, b)

Creates a new pair with the first element replaced by the given value.

let p = #(1, 2)
let assert pair.replace_first(p, 3) = #(3, 2)

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pub fn replace_second(pair: #(a, b), second: c) -> #(a, c)

Creates a new pair with the second element replaced by the given value.

let p = #(1, 2)
let assert pair.replace_second(p, 3) = #(1, 3)

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pub fn twin(value: a) -> #(a, a)

Creates a pair with the given value as both the first and second elements.

let assert pair.twin(1) = #(1, 1)