diff options
Diffstat (limited to 'lib/stdlib/src/maps.erl')
| -rw-r--r-- | lib/stdlib/src/maps.erl | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/lib/stdlib/src/maps.erl b/lib/stdlib/src/maps.erl index fd6d56fa47..ba4d6a5c87 100644 --- a/lib/stdlib/src/maps.erl +++ b/lib/stdlib/src/maps.erl @@ -23,7 +23,9 @@ fold/3, map/2, size/1, - without/2 + without/2, + with/2, + get/3 ]). @@ -132,16 +134,31 @@ to_list(_) -> erlang:nif_error(undef). update(_,_,_) -> erlang:nif_error(undef). --spec values(Map) -> Keys when +-spec values(Map) -> Values when Map :: map(), - Keys :: [Key], - Key :: term(). + Values :: [Value], + Value :: term(). values(_) -> erlang:nif_error(undef). %%% End of BIFs +-spec get(Key, Map, Default) -> Value | Default when + Key :: term(), + Map :: map(), + Value :: term(), + Default :: term(). + +get(Key, Map, Default) -> + case maps:find(Key, Map) of + {ok, Value} -> + Value; + error -> + Default + end. + + -spec fold(Fun,Init,Map) -> Acc when Fun :: fun((K, V, AccIn) -> AccOut), Init :: term(), @@ -185,3 +202,13 @@ size(Map) when is_map(Map) -> without(Ks, M) when is_list(Ks), is_map(M) -> maps:from_list([{K,V}||{K,V} <- maps:to_list(M), not lists:member(K, Ks)]). + + +-spec with(Ks, Map1) -> Map2 when + Ks :: [K], + Map1 :: map(), + Map2 :: map(), + K :: term(). + +with(Ks, M) when is_list(Ks), is_map(M) -> + maps:from_list([{K,V}||{K,V} <- maps:to_list(M), lists:member(K, Ks)]). |