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retired
A standard library for the Gleam programming language
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src/gleam@option.erl
-module(gleam@option).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).
-export([all/1, is_some/1, is_none/1, to_result/2, from_result/1, unwrap/2, lazy_unwrap/2, map/2, flatten/1, then/2, 'or'/2, lazy_or/2, values/1]).
-export_type([option/1]).
-type option(GB) :: {some, GB} | none.
-spec do_all(list(option(GC)), list(GC)) -> option(list(GC)).
do_all(List, Acc) ->
case List of
[] ->
{some, Acc};
[X | Rest] ->
Accumulate = fun(Acc@1, Item) -> case {Acc@1, Item} of
{{some, Values}, {some, Value}} ->
{some, [Value | Values]};
{_, _} ->
none
end end,
Accumulate(do_all(Rest, Acc), X)
end.
-spec all(list(option(GI))) -> option(list(GI)).
all(List) ->
do_all(List, []).
-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(GR), GU) -> {ok, GR} | {error, GU}.
to_result(Option, E) ->
case Option of
{some, A} ->
{ok, A};
_ ->
{error, E}
end.
-spec from_result({ok, GX} | {error, any()}) -> option(GX).
from_result(Result) ->
case Result of
{ok, A} ->
{some, A};
_ ->
none
end.
-spec unwrap(option(HC), HC) -> HC.
unwrap(Option, Default) ->
case Option of
{some, X} ->
X;
none ->
Default
end.
-spec lazy_unwrap(option(HE), fun(() -> HE)) -> HE.
lazy_unwrap(Option, Default) ->
case Option of
{some, X} ->
X;
none ->
Default()
end.
-spec map(option(HG), fun((HG) -> HI)) -> option(HI).
map(Option, Fun) ->
case Option of
{some, X} ->
{some, Fun(X)};
none ->
none
end.
-spec flatten(option(option(HK))) -> option(HK).
flatten(Option) ->
case Option of
{some, X} ->
X;
none ->
none
end.
-spec then(option(HO), fun((HO) -> option(HQ))) -> option(HQ).
then(Option, Fun) ->
case Option of
{some, X} ->
Fun(X);
none ->
none
end.
-spec 'or'(option(HT), option(HT)) -> option(HT).
'or'(First, Second) ->
case First of
{some, _} ->
First;
none ->
Second
end.
-spec lazy_or(option(HX), fun(() -> option(HX))) -> option(HX).
lazy_or(First, Second) ->
case First of
{some, _} ->
First;
none ->
Second()
end.
-spec do_values(list(option(IB)), list(IB)) -> list(IB).
do_values(List, Acc) ->
case List of
[] ->
Acc;
[X | Xs] ->
Accumulate = fun(Acc@1, Item) -> case Item of
{some, Value} ->
[Value | Acc@1];
none ->
Acc@1
end end,
Accumulate(do_values(Xs, Acc), X)
end.
-spec values(list(option(IG))) -> list(IG).
values(Options) ->
do_values(Options, []).