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

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

-spec first({M, any()}) -> M.
first(Pair) ->
    {A, _} = Pair,
    A.

-spec second({any(), P}) -> P.
second(Pair) ->
    {_, A} = Pair,
    A.

-spec swap({Q, R}) -> {R, Q}.
swap(Pair) ->
    {A, B} = Pair,
    {B, A}.

-spec map_first({S, T}, fun((S) -> U)) -> {U, T}.
map_first(Pair, Fun) ->
    {A, B} = Pair,
    {Fun(A), B}.

-spec map_second({V, W}, fun((W) -> X)) -> {V, X}.
map_second(Pair, Fun) ->
    {A, B} = Pair,
    {A, Fun(B)}.