-module(gleam@pair).
-compile(no_auto_import).

-export([first/1, second/1, swap/1, map_first/2, map_second/2]).

-spec first({DU, any()}) -> DU.
first(Pair) ->
    {A, _@1} = Pair,
    A.

-spec second({any(), DX}) -> DX.
second(Pair) ->
    {_@1, A} = Pair,
    A.

-spec swap({DY, DZ}) -> {DZ, DY}.
swap(Pair) ->
    {A, B} = Pair,
    {B, A}.

-spec map_first({EA, EB}, fun((EA) -> EC)) -> {EC, EB}.
map_first(Pair, Fun) ->
    {A, B} = Pair,
    {Fun(A), B}.

-spec map_second({ED, EE}, fun((EE) -> EF)) -> {ED, EF}.
map_second(Pair, Fun) ->
    {A, B} = Pair,
    {A, Fun(B)}.