From: Simon Peyton Jones <simonpj@microsoft.com>
Date: Thu, 28 Apr 2011 08:24:30 +0000 (+0100)
Subject: Use 'default' rather than 'generic' for default-method signatures
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=60401bfe16c49ef2e06e5e81fd58e030bea02013

Use 'default' rather than 'generic' for default-method signatures

Also get rid of the old {| |} brackets in the lexer.

Fewer keywords!
---

diff --git a/compiler/parser/Lexer.x b/compiler/parser/Lexer.x
index e86687b..338af4c 100644
--- a/compiler/parser/Lexer.x
+++ b/compiler/parser/Lexer.x
@@ -335,11 +335,6 @@ $tab+         { warn Opt_WarnTabs (text "Warning: Tab character") }
          { token ITcubxparen }
 }
 
-<0> {
-  "{|" / { ifExtension genericsEnabled } { token ITocurlybar }
-  "|}" / { ifExtension genericsEnabled } { token ITccurlybar }
-}
-
 <0,option_prags> {
   \(					{ special IToparen }
   \)					{ special ITcparen }
@@ -431,7 +426,6 @@ data Token
   | ITderiving
   | ITdo
   | ITelse
-  | ITgeneric
   | IThiding
   | ITif
   | ITimport
@@ -636,7 +630,6 @@ reservedWordsFM = listToUFM $
 	( "deriving",	ITderiving, 	0 ), 
 	( "do",		ITdo, 		0 ),       
 	( "else",	ITelse, 	0 ),     
-	( "generic",	ITgeneric, 	bit genericsBit ),     
 	( "hiding",	IThiding, 	0 ),
 	( "if",		ITif, 		0 ),       
 	( "import",	ITimport, 	0 ),   
@@ -1753,8 +1746,10 @@ setAlrExpectingOCurly b = P $ \s -> POk (s {alr_expecting_ocurly = b}) ()
 -- -fglasgow-exts or -XParallelArrays) are represented by a bitmap stored in an unboxed
 -- integer
 
-genericsBit :: Int
-genericsBit = 0 -- {|, |} and "generic"
+-- The "genericsBit" is now unused, available for others
+-- genericsBit :: Int
+-- genericsBit = 0 -- {|, |} and "generic"
+
 ffiBit :: Int
 ffiBit	   = 1
 parrBit :: Int
@@ -1805,8 +1800,6 @@ nondecreasingIndentationBit = 25
 
 always :: Int -> Bool
 always           _     = True
-genericsEnabled :: Int -> Bool
-genericsEnabled  flags = testBit flags genericsBit
 parrEnabled :: Int -> Bool
 parrEnabled      flags = testBit flags parrBit
 arrowsEnabled :: Int -> Bool
@@ -1875,8 +1868,7 @@ mkPState flags buf loc =
       alr_justClosedExplicitLetBlock = False
     }
     where
-      bitmap =     genericsBit       `setBitIf` xopt Opt_Generics flags
-               .|. ffiBit            `setBitIf` xopt Opt_ForeignFunctionInterface flags
+      bitmap =     ffiBit            `setBitIf` xopt Opt_ForeignFunctionInterface flags
                .|. parrBit           `setBitIf` xopt Opt_ParallelArrays  flags
                .|. arrowsBit         `setBitIf` xopt Opt_Arrows          flags
                .|. thBit             `setBitIf` xopt Opt_TemplateHaskell flags
diff --git a/compiler/parser/Parser.y.pp b/compiler/parser/Parser.y.pp
index 078cfa4..e009071 100644
--- a/compiler/parser/Parser.y.pp
+++ b/compiler/parser/Parser.y.pp
@@ -216,7 +216,6 @@ incorrect.
  'deriving' 	{ L _ ITderiving }
  'do' 		{ L _ ITdo }
  'else' 	{ L _ ITelse }
- 'generic' 	{ L _ ITgeneric }
  'hiding' 	{ L _ IThiding }
  'if' 		{ L _ ITif }
  'import' 	{ L _ ITimport }
@@ -722,6 +721,11 @@ decl_cls  :: { Located (OrdList (LHsDecl RdrName)) }
 decl_cls  : at_decl_cls		        { LL (unitOL (L1 (TyClD (unLoc $1)))) }
 	  | decl                        { $1 }
 
+	  -- A 'default' signature used with the generic-programming extension
+          | 'default' infixexp '::' sigtypedoc
+                    {% do { (TypeSig l ty) <- checkValSig $2 $4
+                          ; return (LL $ unitOL (LL $ SigD (GenericSig l ty))) } }
+
 decls_cls :: { Located (OrdList (LHsDecl RdrName)) }	-- Reversed
 	  : decls_cls ';' decl_cls	{ LL (unLoc $1 `appOL` unLoc $3) }
 	  | decls_cls ';'		{ LL (unLoc $1) }
@@ -1233,11 +1237,9 @@ gdrh :: { LGRHS RdrName }
 	: '|' guardquals '=' exp  	{ sL (comb2 $1 $>) $ GRHS (unLoc $2) $4 }
 
 sigdecl :: { Located (OrdList (LHsDecl RdrName)) }
-        : 'generic' infixexp '::' sigtypedoc
-                        {% do (TypeSig l ty) <- checkValSig $2 $4
-                        ; return (LL $ unitOL (LL $ SigD (GenericSig l ty))) }
+        : 
 	-- See Note [Declaration/signature overlap] for why we need infixexp here
-	| infixexp '::' sigtypedoc
+	  infixexp '::' sigtypedoc
                         {% do s <- checkValSig $1 $3 
                         ; return (LL $ unitOL (LL $ SigD s)) }
 	| var ',' sig_vars '::' sigtypedoc
diff --git a/compiler/rename/RnBinds.lhs b/compiler/rename/RnBinds.lhs
index a18dfce..b0dd3b5 100644
--- a/compiler/rename/RnBinds.lhs
+++ b/compiler/rename/RnBinds.lhs
@@ -713,7 +713,9 @@ renameSig mb_names sig@(TypeSig v ty)
 	; return (TypeSig new_v new_ty) }
 
 renameSig mb_names sig@(GenericSig v ty)
-  = do	{ new_v <- lookupSigOccRn mb_names sig v
+  = do	{ generics_on <- xoptM Opt_Generics
+        ; unless generics_on (addErr (genericSigErr sig))
+        ; new_v <- lookupSigOccRn mb_names sig v
 	; new_ty <- rnHsSigType (quotes (ppr v)) ty
 	; return (GenericSig new_v new_ty) } -- JPM: ?
 
@@ -838,6 +840,11 @@ misplacedSigErr (L loc sig)
   = addErrAt loc $
     sep [ptext (sLit "Misplaced") <+> hsSigDoc sig <> colon, ppr sig]
 
+genericSigErr :: Sig RdrName -> SDoc
+genericSigErr sig = vcat [ hang (ptext (sLit "Unexpected generic default signature:"))
+                              2 (ppr sig)
+                         , ptext (sLit "Use -XGenerics to enable generic default signatures") ] 
+
 methodBindErr :: HsBindLR RdrName RdrName -> SDoc
 methodBindErr mbind
  =  hang (ptext (sLit "Pattern bindings (except simple variables) not allowed in instance declarations"))
@@ -852,4 +859,5 @@ nonStdGuardErr :: [LStmtLR Name Name] -> SDoc
 nonStdGuardErr guards
   = hang (ptext (sLit "accepting non-standard pattern guards (use -XPatternGuards to suppress this message)"))
        4 (interpp'SP guards)
+
 \end{code}