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

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

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

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

-spec swap({CV, CW}) -> {CW, CV}.
swap(Pair) ->
    {A, B} = Pair,
    {B, A}.

-spec map_first({CX, CY}, fun((CX) -> CZ)) -> {CZ, CY}.
map_first(Pair, Fun) ->
    {A, B} = Pair,
    {Fun(A), B}.

-spec map_second({DA, DB}, fun((DB) -> DC)) -> {DA, DC}.
map_second(Pair, Fun) ->
    {A, B} = Pair,
    {A, Fun(B)}.