gleam/pair

first

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

Returns the first element in a pair.

> first(#(1, 2))
1

</>

pub fn map_first(
  of pair: #(a, b),
  with fun: fn(a) -> c,
) -> #(c, b)

Returns a new pair with the first element having had with applied to it.

> #(1, 2) |> map_first(fn(n) { n * 2 })
#(2, 2)

</>

pub fn map_second(
  of pair: #(a, b),
  with fun: fn(b) -> c,
) -> #(a, c)

Returns a new pair with the second element having had with applied to it.

> #(1, 2) |> map_second(fn(n) { n * 2 })
#(1, 4)

</>

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

Returns the second element in a pair.

> second(#(1, 2))
2

</>

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

Returns a new pair with the elements swapped.

> swap(#(1, 2))
#(2, 1)