, get/2
, set/3
, update/3
+ , pop/2
, iter/2
, map/2
, filter/2
empty() ->
[].
+-spec get(t(K, V), K) ->
+ hope_option:t(V).
get(T, K) ->
case lists:keyfind(K, 1, T)
of false -> none
; {K, V} -> {some, V}
end.
+-spec set(t(K, V), K, V) ->
+ t(K, V).
set(T, K, V) ->
lists:keystore(K, 1, T, {K, V}).
+-spec update(t(K, V), K, fun((hope_option:t(V)) -> V)) ->
+ t(K, V).
update(T, K, F) ->
V1Opt = get(T, K),
V2 = F(V1Opt),
% TODO: Eliminate the 2nd lookup.
set(T, K, V2).
-iter(T, Map1) ->
- Map2 = lift_map_into_list(Map1),
- lists:foreach(Map2, T).
-
-map(T, Map1) ->
- Map2 = lift_map_into_list(Map1),
- lists:map(Map2, T).
-
-filter(T, Map1) ->
- Map2 = lift_map_into_list(Map1),
- lists:filter(Map2, T).
+-spec pop(t(K, V), K) ->
+ {hope_option:t(V), t(K, V)}.
+pop(T1, K) ->
+ case lists:keytake(K, 1, T1)
+ of {value, {K, V}, T2} -> {{some, V}, T2}
+ ; false -> {none , T1}
+ end.
+-spec iter(t(K, V), fun((K, V) -> ok)) ->
+ ok.
+iter(T, F1) ->
+ F2 = lift_map(F1),
+ lists:foreach(F2, T).
+
+-spec map(t(K, V), fun((K, V) -> V)) ->
+ t(K, V).
+map(T, F1) ->
+ F2 = fun ({K, _}=X) -> {K, apply_map(F1, X)} end,
+ lists:map(F2, T).
+
+-spec filter(t(K, V), fun((K, V) -> boolean())) ->
+ t(K, V).
+filter(T, F1) ->
+ F2 = lift_map(F1),
+ lists:filter(F2, T).
+
+-spec fold(t(K, V), fun((K, V, Acc) -> Acc), Acc) ->
+ Acc.
fold(T, F1, Accumulator) ->
F2 = fun ({K, V}, Acc) -> F1(K, V, Acc) end,
- lists:foldl(F2, T, Accumulator).
+ lists:foldl(F2, Accumulator, T).
+-spec to_kv_list(t(K, V)) ->
+ [{K, V}].
to_kv_list(T) ->
T.
+-spec of_kv_list([{K, V}]) ->
+ t(K, V).
of_kv_list(List) ->
% TODO: Decide if validation is to be done here. Do so if yes.
List.
%% Helpers
%% ============================================================================
-lift_map_into_list(Map) ->
- fun ({K, V}) -> {K, Map(K, V)} end.
+-spec lift_map(F) ->
+ G
+ when F :: fun(( K, V1 ) -> V2)
+ , G :: fun(({K, V1}) -> V2)
+ .
+lift_map(F) ->
+ fun (X) -> apply_map(F, X) end.
+
+-spec apply_map(fun((K, V1) -> V2), {K, V1}) ->
+ V2.
+apply_map(F, {K, V}) ->
+ F(K, V).