font-lock: remove useless rule for (,) and (->)

The (,) and (->) don't have much use in PureScript, nor in Haskell for
that matter. In Haskell (,) was a prefix notation for tuple
construction, but in PureScript this operator isn't a thing. Both
trigger "syntax error" in PureScript (and (->) doesn't work even in
Haskell).

Indeed a debatable rule. Let's just remove it.

Author: Hi-Angel

purescript-font-lock.el

@@ -230,8 +230,7 @@ Returns keywords suitable for `font-lock-keywords'."
       (,topdecl-sym  (2 (symbol-value 'purescript-definition-face)))
       (,topdecl-sym2 (1 (symbol-value 'purescript-definition-face)))
 
-      ;; These four are debatable...
-      ("(\\(,*\\|->\\))" 0 (symbol-value 'purescript-constructor-face))
+      ;; This one is debatable…
       ("\\[\\]" 0 (symbol-value 'purescript-constructor-face))
       ;; Expensive.
       (,qvarid 0 (symbol-value 'purescript-default-face))