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

-export([is_some/1, is_none/1, to_result/2, from_result/1, unwrap/2, map/2, flatten/1, then/2, 'or'/2]).
-export_type([option/1]).

-type option(IU) :: {some, IU} | none.

-spec is_some(option(any())) -> boolean().
is_some(Option) ->
    Option /= none.

-spec is_none(option(any())) -> boolean().
is_none(Option) ->
    Option =:= none.

-spec to_result(option(IZ), JC) -> {ok, IZ} | {error, JC}.
to_result(Option, E) ->
    case Option of
        {some, A} ->
            {ok, A};

        _ ->
            {error, E}
    end.

-spec from_result({ok, JF} | {error, any()}) -> option(JF).
from_result(Result) ->
    case Result of
        {ok, A} ->
            {some, A};

        _ ->
            none
    end.

-spec unwrap(option(JK), JK) -> JK.
unwrap(Option, Default) ->
    case Option of
        {some, X} ->
            X;

        none ->
            Default
    end.

-spec map(option(JM), fun((JM) -> JO)) -> option(JO).
map(Option, Fun) ->
    case Option of
        {some, X} ->
            {some, Fun(X)};

        none ->
            none
    end.

-spec flatten(option(option(JQ))) -> option(JQ).
flatten(Option) ->
    case Option of
        {some, X} ->
            X;

        none ->
            none
    end.

-spec then(option(JU), fun((JU) -> option(JW))) -> option(JW).
then(Option, Fun) ->
    case Option of
        {some, X} ->
            Fun(X);

        none ->
            none
    end.

-spec 'or'(option(JZ), option(JZ)) -> option(JZ).
'or'(First, Second) ->
    case First of
        {some, _} ->
            First;

        none ->
            Second
    end.