X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FMatchCon.lhs;h=a84c96d198cc08fabf27dd60782ef06d9189ab45;hb=ed75b2fd12799f62ea76ae43ebaa46d04f70db3d;hp=62ed087648247219fded6b54aac75807c697586e;hpb=23f40f0e9be6d4aa5cf9ea31d73f4013f8e7b4bd;p=ghc-hetmet.git

diff --git a/ghc/compiler/deSugar/MatchCon.lhs b/ghc/compiler/deSugar/MatchCon.lhs
index 62ed087..a84c96d 100644
--- a/ghc/compiler/deSugar/MatchCon.lhs
+++ b/ghc/compiler/deSugar/MatchCon.lhs
@@ -22,7 +22,7 @@ import DsUtils
 import Id		( Id )
 import Type             ( Type )
 import ListSetOps	( equivClassesByUniq )
-import SrcLoc		( unLoc )
+import SrcLoc		( unLoc, Located(..) )
 import Unique		( Uniquable(..) )
 import Outputable
 \end{code}
@@ -86,12 +86,23 @@ matchConFamily (var:vars) ty eqns_info
   = let
 	-- Sort into equivalence classes by the unique on the constructor
 	-- All the EqnInfos should start with a ConPat
-	eqn_groups = equivClassesByUniq get_uniq eqns_info
-	get_uniq (EqnInfo { eqn_pats = ConPatOut data_con _ _ _ _ _ : _}) = getUnique data_con
+	groups = equivClassesByUniq get_uniq eqns_info
+	get_uniq (EqnInfo { eqn_pats = ConPatOut (L _ data_con) _ _ _ _ _ : _}) = getUnique data_con
+
+	-- Get the wrapper from the head of each group.  We're going to
+	-- use it as the pattern in this case expression, so we need to 
+	-- ensure that any type variables it mentions in the pattern are
+	-- in scope.  So we put its wrappers outside the case, and
+	-- zap the wrapper for it. 
+	wraps :: [CoreExpr -> CoreExpr]
+	wraps = map (eqn_wrap . head) groups
+
+	groups' = [ eqn { eqn_wrap = idWrapper } : eqns | eqn:eqns <- groups ]
     in
 	-- Now make a case alternative out of each group
-    mappM (match_con vars ty) eqn_groups	`thenDs` \ alts ->
-    returnDs (mkCoAlgCaseMatchResult var ty alts)
+    mappM (match_con vars ty) groups'	`thenDs` \ alts ->
+    returnDs (adjustMatchResult (foldr (.) idWrapper wraps) $
+	      mkCoAlgCaseMatchResult var ty alts)
 \end{code}
 
 And here is the local function that does all the work.  It is
@@ -105,35 +116,28 @@ wouldn't).  Cf.~@shift_lit_pats@ in @MatchLits@.
 \begin{code}
 match_con vars ty eqns
   = do	{ -- Make new vars for the con arguments; avoid new locals where possible
-	  arg_vars <- selectMatchVars (map unLoc arg_pats1) arg_tys
-
-	; match_result <- match (arg_vars ++ vars) ty (shiftEqns eqns)
-
-	; binds <- mapM ds_binds [ bind | ConPatOut _ _ _ bind _ _ <- pats,
-					  not (isEmptyLHsBinds bind) ]
-
-	; let match_result' = bindInMatchResult (line_up other_pats) $
-			      mkCoLetsMatchResult binds match_result
-	
-	; return (data_con, tvs1 ++ dicts1 ++ arg_vars, match_result') }
+	  arg_vars     <- selectMatchVars (map unLoc arg_pats1) arg_tys
+	; eqns'        <- mapM shift eqns 
+	; match_result <- match (arg_vars ++ vars) ty eqns'
+	; return (con, tvs1 ++ dicts1 ++ arg_vars, match_result) }
   where
-    pats@(pat1 : other_pats) = map firstPat eqns
-    ConPatOut data_con tvs1 dicts1 _ (PrefixCon arg_pats1) pat_ty = pat1
-
-    ds_binds bind = do { prs <- dsHsNestedBinds bind; return (Rec prs) }
+    ConPatOut (L _ con) tvs1 dicts1 _ (PrefixCon arg_pats1) pat_ty = firstPat (head eqns)
 
-    line_up pats 
-	| null tvs1 && null dicts1 = []		-- Common case
-	| otherwise = [ pr | ConPatOut _ ts ds _ _ _ <- pats,
-			     pr <- (ts `zip` tvs1) ++ (ds `zip` dicts1)]
+    shift eqn@(EqnInfo { eqn_wrap = wrap, 
+		         eqn_pats = ConPatOut _ tvs ds bind (PrefixCon arg_pats) _ : pats })
+	= do { prs <- dsHsNestedBinds bind
+	     ; return (eqn { eqn_wrap = wrap . wrapBinds (tvs `zip` tvs1) 
+					     . wrapBinds (ds  `zip` dicts1)
+					     . mkDsLet (Rec prs),
+			     eqn_pats = map unLoc arg_pats ++ pats }) }
 
      	-- Get the arg types, which we use to type the new vars
 	-- to match on, from the "outside"; the types of pats1 may 
 	-- be more refined, and hence won't do
-    arg_tys = substTys (zipTopTvSubst (dataConTyVars data_con) inst_tys)
-		       (dataConOrigArgTys data_con)
-    inst_tys | isVanillaDataCon data_con = tcTyConAppArgs pat_ty	-- Newtypes opaque!
-	     | otherwise		 = mkTyVarTys tvs1
+    arg_tys = substTys (zipTopTvSubst (dataConTyVars con) inst_tys)
+		       (dataConOrigArgTys con)
+    inst_tys | isVanillaDataCon con = tcTyConAppArgs pat_ty	-- Newtypes opaque!
+	     | otherwise	    = mkTyVarTys tvs1
 \end{code}
 
 Note [Existentials in shift_con_pat]