Merge pull request #682 from gracjan/pr-prevent-keyword-symbols-redefinition

Prevent keyword symbols redefinition

Author: gracjan

haskell-font-lock.el

@@ -253,8 +253,10 @@ Returns keywords suitable for `font-lock-keywords'."
             (,topdecl-var  (1 'haskell-definition-face))
             (,topdecl-var2 (2 'haskell-definition-face))
             (,topdecl-bangpat  (1 'haskell-definition-face))
-            (,topdecl-sym  (2 'haskell-definition-face))
-            (,topdecl-sym2 (1 'haskell-definition-face))
+            (,topdecl-sym  (2 (unless (member (match-string 2) '("\\" "=" "->" "→" "<-" "←" "::" "∷" "," ";" "`"))
+                                'haskell-definition-face)))
+            (,topdecl-sym2 (1 (unless (member (match-string 1) '("\\" "=" "->" "→" "<-" "←" "::" "∷" "," ";" "`"))
+                                'haskell-definition-face)))
 
             ;; These four are debatable...
             ("(\\(,*\\|->\\))" 0 'haskell-constructor-face)
@@ -269,7 +271,8 @@ Returns keywords suitable for `font-lock-keywords'."
 
             (,conid 0 'haskell-constructor-face)
 
-            (,sym 0 (if (eq (char-after (match-beginning 0)) ?:)
+            (,sym 0 (if (and (eq (char-after (match-beginning 0)) ?:)
+                             (not (member (match-string 0) '("::" "∷"))))
                         'haskell-constructor-face
                       'haskell-operator-face))))
     keywords))