[project @ 2002-02-12 03:52:08 by chak]

[ghc-hetmet.git] / ghc / compiler / parser / Parser.y

diff --git a/ghc/compiler/parser/Parser.y b/ghc/compiler/parser/Parser.y
index e98b1ff..a478ec4 100644 (file)
--- a/ghc/compiler/parser/Parser.y
+++ b/ghc/compiler/parser/Parser.y
@@ -1,6 +1,6 @@
 {-                                                             -*-haskell-*-
 -----------------------------------------------------------------------------
-$Id: Parser.y,v 1.86 2002/02/11 15:16:26 simonpj Exp $
+$Id: Parser.y,v 1.87 2002/02/12 03:52:08 chak Exp $
 
 Haskell grammar.
 
@@ -389,15 +389,25 @@ topdecl :: { RdrBinding }
 --     (Eq a, Ord b) => T a b
 -- Rather a lot of inlining here, else we get reduce/reduce errors
 tycl_hdr :: { (RdrNameContext, RdrName, [RdrNameHsTyVar]) }
-       : '(' comma_types1 ')' '=>' tycon tv_bndrs      {% mapP checkPred $2    `thenP` \ cxt ->
+       : '(' comma_types1 ')' '=>' gtycon tv_bndrs     {% mapP checkPred $2    `thenP` \ cxt ->
                                                           returnP (cxt, $5, $6) }
-       | qtycon atypes1 '=>' tycon atypes0             {% checkTyVars $5       `thenP` \ tvs ->
+          -- qtycon for the class below name would lead to many s/r conflicts
+         --   FIXME: does the renamer pick up all wrong forms and raise an
+         --          error 
+       | gtycon atypes1 '=>' gtycon atypes0            {% checkTyVars $5       `thenP` \ tvs ->
                                                           returnP ([HsClassP $1 $2], $4, tvs) }
-       | qtycon  atypes0                               {% checkTyVars $2       `thenP` \ tvs ->
+       | gtycon  atypes0                               {% checkTyVars $2       `thenP` \ tvs ->
                                                           returnP ([], $1, tvs) }
-               -- We have to have qtycon in this production to avoid s/r conflicts
-               -- with the previous one.  The renamer will complain if we use
-               -- a qualified tycon.
+               -- We have to have qtycon in this production to avoid s/r
+               -- conflicts with the previous one.  The renamer will complain
+               -- if we use a qualified tycon.
+               --
+               -- Using a `gtycon' throughout.  This enables special syntax,
+               -- such as "[]" for tycons as well as tycon ops in
+               -- parentheses.  This is beyond H98, but used repeatedly in
+               -- the Prelude modules.  (So, it would be a good idea to raise
+               -- an error in the renamer if some non-H98 form is used and
+               -- -fglasgow-exts is not given.)  -=chak 
 
 decls  :: { [RdrBinding] }
        : decls ';' decl                { $3 : $1 }