wfcing

src/wfc.erl

@@ -7,16 +7,8 @@
 ]).
 
 -export([
-    
-    zero/0, one/0,
-    add/1, add/2,
-    mul/1, mul/2
 ]).
 
 
 -type sentence() :: wfc_sentence:sentence().
 
-
-%% constructors
--spec 
-zero() 

src/wfc_sentence.erl

@@ -26,7 +26,7 @@
 %% constructors
 %%--------------------------
 
--spec zero() :: sentence().
+-spec zero() -> sentence().
 
 zero() ->
     {s, []}.
@@ -60,16 +60,34 @@ to_list({s, Words}) -> {ok, Words};
 to_list(Bad)        -> {error, wfc_utils:str("wfc_sentence:to_list: bad sentence: ~tp", [Bad])}.
 
 
+
+-spec validate(sentence()) -> ok | {error, string()}.
+
+validate({s, [W | Rest]}) ->
+    case wfc_word:validate(W) of
+        ok    -> validate({s, Rest});
+        Error -> Error
+    end;
+validate({s, []}) ->
+    ok;
+validate(Bad) ->
+    {error, wfc_utils:str("wfc_sentence:validate: bad sentence: ~tp", [Bad])}.
+
+
 %%---------------------------
 %% prim ops
 %%---------------------------
 
-add({s, X}, {s, Y}) -> {s, disjoint_union(X, Y)}.
+-spec add(sentence(), sentence()) -> sentence().
 
-disjoint_union(X, Y) ->
+add({s, X}, {s, Y}) -> {s, symdiff(X, Y)}.
+
+symdiff(X, Y) ->
     ordsets:subtract(ordsets:union(X, Y),
                      ordsets:intersection(X, Y)).
 
 
+-spec add([sentence()]) -> sentence().
+
 add([S | Rest]) -> add(S, add(Rest));
 add([])         -> zero().

src/wfc_word.erl

@@ -108,6 +108,3 @@ mul({w, X}, {w, Y}) ->
 
 mul([Word | Rest]) -> mul(Word, mul(Rest));
 mul([])            -> one().
-
-
-add(