X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FdeSugar%2FMatch.lhs;h=ca18706f229fc388cf5ca19e83cf3e96688ee801;hp=d793343e4177b8ec2180e7420265ab8d05fcc8c6;hb=a8427a4125e9b78e88a487eeabf018f1c6e8bc08;hpb=3cec5683766a13019c2835a4e79cc7e7dc066b96

diff --git a/compiler/deSugar/Match.lhs b/compiler/deSugar/Match.lhs
index d793343..ca18706 100644
--- a/compiler/deSugar/Match.lhs
+++ b/compiler/deSugar/Match.lhs
@@ -1,40 +1,39 @@
 %
+% (c) The University of Glasgow 2006
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-\section[Main_match]{The @match@ function}
+
+The @match@ function
 
 \begin{code}
 module Match ( match, matchEquations, matchWrapper, matchSimply, matchSinglePat ) where
 
 #include "HsVersions.h"
 
-import DynFlags	( DynFlag(..), dopt )
+import DynFlags
 import HsSyn		
-import TcHsSyn		( mkVanillaTuplePat, hsPatType )
-import Check            ( check, ExhaustivePat )
+import TcHsSyn
+import Check
 import CoreSyn
-import Literal		( Literal )
-import CoreUtils	( bindNonRec, exprType )
+import Literal
+import CoreUtils
 import DsMonad
-import DsBinds		( dsLHsBinds, dsCoercion )
-import DsGRHSs		( dsGRHSs )
+import DsBinds
+import DsGRHSs
 import DsUtils
-import Id		( idName, idType, Id )
-import DataCon		( DataCon )
-import MatchCon		( matchConFamily )
-import MatchLit		( matchLiterals, matchNPlusKPats, matchNPats, 
-			  tidyLitPat, tidyNPat, hsLitKey, hsOverLitKey )
-import PrelInfo		( pAT_ERROR_ID )
-import TcType		( Type )
-import Type		( splitFunTysN, coreEqType )
-import TysWiredIn	( consDataCon, mkListTy, unitTy,
-			  tupleCon, parrFakeCon, mkPArrTy )
-import BasicTypes	( Boxity(..) )
-import ListSetOps	( equivClasses, runs )
-import SrcLoc		( unLoc, Located(..) )
-import Maybes		( isJust )
-import Util             ( lengthExceeds, notNull )
-import Name		( Name )
+import Id
+import DataCon
+import MatchCon
+import MatchLit
+import PrelInfo
+import Type
+import TysWiredIn
+import BasicTypes
+import ListSetOps
+import SrcLoc
+import Maybes
+import Util
+import Name
 import Outputable
 \end{code}
 
@@ -124,8 +123,8 @@ pp_context (DsMatchContext kind _loc) msg rest_of_msg_fun
   where
     (ppr_match, pref)
 	= case kind of
-	     FunRhs fun -> (pprMatchContext kind, \ pp -> ppr fun <+> pp)
-	     other	-> (pprMatchContext kind, \ pp -> pp)
+	     FunRhs fun _ -> (pprMatchContext kind, \ pp -> ppr fun <+> pp)
+	     other	  -> (pprMatchContext kind, \ pp -> pp)
 
 ppr_pats pats = sep (map ppr pats)
 
@@ -254,7 +253,7 @@ match :: [Id]		  -- Variables rep'ing the exprs we're matching with
       -> DsM MatchResult  -- Desugared result!
 
 match [] ty eqns
-  = ASSERT( not (null eqns) )
+  = ASSERT2( not (null eqns), ppr ty )
     returnDs (foldr1 combineMatchResults match_results)
   where
     match_results = [ ASSERT( null (eqn_pats eqn) ) 
@@ -392,7 +391,7 @@ tidy1 :: Id 			-- The Id being scrutinised
 
 tidy1 v (ParPat pat)      = tidy1 v (unLoc pat) 
 tidy1 v (SigPatOut pat _) = tidy1 v (unLoc pat) 
-tidy1 v (WildPat ty)      = returnDs (idWrapper, WildPat ty)
+tidy1 v (WildPat ty)      = returnDs (idDsWrapper, WildPat ty)
 
 	-- case v of { x -> mr[] }
 	-- = case v of { _ -> let x=v in mr[] }
@@ -427,7 +426,7 @@ tidy1 v (LazyPat pat)
 	; returnDs (mkDsLets sel_binds, WildPat (idType v)) }
 
 tidy1 v (ListPat pats ty)
-  = returnDs (idWrapper, unLoc list_ConPat)
+  = returnDs (idDsWrapper, unLoc list_ConPat)
   where
     list_ty     = mkListTy ty
     list_ConPat = foldr (\ x y -> mkPrefixConPat consDataCon [x, y] list_ty)
@@ -437,38 +436,29 @@ tidy1 v (ListPat pats ty)
 -- Introduce fake parallel array constructors to be able to handle parallel
 -- arrays with the existing machinery for constructor pattern
 tidy1 v (PArrPat pats ty)
-  = returnDs (idWrapper, unLoc parrConPat)
+  = returnDs (idDsWrapper, unLoc parrConPat)
   where
     arity      = length pats
     parrConPat = mkPrefixConPat (parrFakeCon arity) pats (mkPArrTy ty)
 
 tidy1 v (TuplePat pats boxity ty)
-  = returnDs (idWrapper, unLoc tuple_ConPat)
+  = returnDs (idDsWrapper, unLoc tuple_ConPat)
   where
     arity = length pats
     tuple_ConPat = mkPrefixConPat (tupleCon boxity arity) pats ty
 
-tidy1 v (DictPat dicts methods)
-  = case num_of_d_and_ms of
-	0 -> tidy1 v (TuplePat [] Boxed unitTy) 
-	1 -> tidy1 v (unLoc (head dict_and_method_pats))
-	_ -> tidy1 v (mkVanillaTuplePat dict_and_method_pats Boxed)
-  where
-    num_of_d_and_ms	 = length dicts + length methods
-    dict_and_method_pats = map nlVarPat (dicts ++ methods)
-
 -- LitPats: we *might* be able to replace these w/ a simpler form
 tidy1 v (LitPat lit)
-  = returnDs (idWrapper, tidyLitPat lit)
+  = returnDs (idDsWrapper, tidyLitPat lit)
 
 -- NPats: we *might* be able to replace these w/ a simpler form
 tidy1 v (NPat lit mb_neg eq lit_ty)
-  = returnDs (idWrapper, tidyNPat lit mb_neg eq lit_ty)
+  = returnDs (idDsWrapper, tidyNPat lit mb_neg eq lit_ty)
 
 -- Everything else goes through unchanged...
 
 tidy1 v non_interesting_pat
-  = returnDs (idWrapper, non_interesting_pat)
+  = returnDs (idDsWrapper, non_interesting_pat)
 \end{code}
 
 \noindent
@@ -610,7 +600,8 @@ JJQC 30-Nov-1997
 
 \begin{code}
 matchWrapper ctxt (MatchGroup matches match_ty)
-  = do	{ eqns_info   <- mapM mk_eqn_info matches
+  = ASSERT( notNull matches )
+    do	{ eqns_info   <- mapM mk_eqn_info matches
 	; new_vars    <- selectMatchVars arg_pats
 	; result_expr <- matchEquations ctxt new_vars eqns_info rhs_ty
 	; return (new_vars, result_expr) }
@@ -715,6 +706,9 @@ data PatGroup
 
 
 groupEquations :: [EquationInfo] -> [[(PatGroup, EquationInfo)]]
+-- If the result is of form [g1, g2, g3], 
+-- (a) all the (pg,eq) pairs in g1 have the same pg
+-- (b) none of the gi are empty
 groupEquations eqns
   = runs same_gp [(patGroup (firstPat eqn), eqn) | eqn <- eqns]
   where