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|
-module(result).
-compile(no_auto_import).
-include_lib("eunit/include/eunit.hrl").
-export([is_ok/1, is_error/1, map/2, map_error/2, flatten/1, flat_map/2, unwrap/2]).
is_ok(Result) ->
case Result of
{error, _} ->
false;
{ok, _} ->
true
end.
-ifdef(TEST).
is_ok_test() ->
expect:true(is_ok({ok, 1})),
expect:false(is_ok({error, 1})).
-endif.
is_error(Result) ->
case Result of
{ok, _} ->
false;
{error, _} ->
true
end.
-ifdef(TEST).
is_error_test() ->
expect:false(is_error({ok, 1})),
expect:true(is_error({error, 1})).
-endif.
map(Result, Fun) ->
case Result of
{ok, X} ->
{ok, Fun(X)};
{error, _} ->
Result
end.
-ifdef(TEST).
map_test() ->
expect:equal(map({ok, 1}, fun(X) -> X + 1 end), {ok, 2}),
expect:equal(map({error, 1}, fun(X) -> X + 1 end), {error, 1}).
-endif.
map_error(Result, Fun) ->
case Result of
{ok, _} ->
Result;
{error, Error} ->
{error, Fun(Error)}
end.
-ifdef(TEST).
map_error_test() ->
expect:equal(map_error({ok, 1}, fun(X) -> X + 1 end), {ok, 1}),
expect:equal(map_error({error, 1}, fun(X) -> X + 1 end), {error, 2}).
-endif.
flatten(Result) ->
case Result of
{ok, X} ->
X;
{error, Error} ->
{error, Error}
end.
-ifdef(TEST).
flatten_test() ->
expect:equal(flatten({ok, {ok, 1}}), {ok, 1}),
expect:equal(flatten({ok, {error, 1}}), {error, 1}),
expect:equal(flatten({error, 1}), {error, 1}),
expect:equal(flatten({error, {error, 1}}), {error, {error, 1}}).
-endif.
flat_map(Result, Fun) ->
case Result of
{ok, X} ->
case Fun(X) of
{ok, Y} ->
{ok, Y};
{error, Y1} ->
{error, Y1}
end;
{error, _} ->
Result
end.
-ifdef(TEST).
flat_map_test() ->
expect:equal(flat_map({error, 1}, fun(X) -> {ok, X + 1} end), {error, 1}),
expect:equal(flat_map({ok, 1}, fun(X) -> {ok, X + 1} end), {ok, 2}),
expect:equal(flat_map({ok, 1}, fun(_) -> {error, 1} end), {error, 1}).
-endif.
unwrap(Result, Default) ->
case Result of
{ok, V} ->
V;
{error, _} ->
Default
end.
-ifdef(TEST).
unwrap_test() ->
expect:equal(unwrap({ok, 1}, 50), 1),
expect:equal(unwrap({error, <<"nope">>}, 50), 50).
-endif.
|
