snowflakes work except define

src/wfc_eval_context.erl

@@ -32,7 +32,62 @@ default() ->
 
 default_snowflakes() ->
     #{<<"and">>     => fun wfc:mul/1,
-      <<"xor">>     => fun wfc:add/1}.
+      <<"xor">>     => fun wfc:add/1,
+      <<"ior">> =>
+            fun IOR([S1 | Rest]) ->
+                    case IOR(Rest) of
+                        {ok, S2} -> {ok, sf_ior(S1, S2)};
+                        Error    -> Error
+                    end;
+                IOR([]) ->
+                    {ok, wfc:one()}
+            end,
+      <<"not">> =>
+            fun ([S]) -> {ok, sf_not(S)};
+                (Bad) -> {error, wfc_utils:str("not/1: wrong number of arguments: ~p", [Bad])}
+            end,
+      <<"implies">> =>
+            fun ([A, B]) -> {ok, sf_implies(A, B)};
+                (Bad)    -> {error, wfc_utils:str("implies/2: wrong number of arguments: ~p", [Bad])}
+            end,
+      <<"impliedby">> =>
+            fun ([A, B]) -> {ok, sf_impliedby(A, B)};
+                (Bad)    -> {error, wfc_utils:str("impliedby/2: wrong number of arguments: ~p", [Bad])}
+            end,
+      <<"iff">> =>
+            fun ([A, B]) -> {ok, sf_iff(A, B)};
+                (Bad)    -> {error, wfc_utils:str("iff/2: wrong number of arguments: ~p", [Bad])}
+            end
+     }.
+
+sf_ior(A, B) ->
+    wfc_sftt:appl_ttf(fun ttf_ior/2, [A, B]).
+
+sf_not(A) ->
+    {ok, Result} = wfc:add([wfc_sentence:one(), A]),
+    Result.
+
+sf_implies(A, B) ->
+    wfc_sftt:appl_ttf(fun ttf_implies/2, [A, B]).
+
+sf_impliedby(A, B) ->
+    sf_implies(B, A).
+
+sf_iff(A, B) ->
+    {ok, Result} = wfc:mul([sf_implies(A, B), sf_impliedby(A, B)]),
+    Result.
+
+ttf_ior(0, 0) -> 0;
+ttf_ior(1, 0) -> 1;
+ttf_ior(0, 1) -> 1;
+ttf_ior(1, 1) -> 1.
+
+ttf_implies(0, 0) -> 1;
+ttf_implies(1, 0) -> 0;
+ttf_implies(0, 1) -> 1;
+ttf_implies(1, 1) -> 1.
+
+
 
 define(Pat, Sentence, Ctx = #ctx{patterns = OldPatterns}) ->
     NewPatterns = maps:put(Pat, Sentence, OldPatterns),