X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FFamInstEnv.lhs;h=b8c82f862328f79e1e7a0af7fcfe43cf946002dc;hb=ecdc15ea7813c43a4d84b7c6554a13c06f210a7e;hp=b851ec1ee64d83c4ea8f27d159b5c0a738cc8f00;hpb=3a2b38084cfea1c88009c4d9236fa403bdda25b4;p=ghc-hetmet.git

diff --git a/compiler/types/FamInstEnv.lhs b/compiler/types/FamInstEnv.lhs
index b851ec1..b8c82f8 100644
--- a/compiler/types/FamInstEnv.lhs
+++ b/compiler/types/FamInstEnv.lhs
@@ -46,13 +46,19 @@ import Maybe
 \begin{code}
 data FamInst 
   = FamInst { fi_fam   :: Name		-- Family name
+		-- INVARIANT: fi_fam = case tyConFamInst_maybe fi_tycon of
+		--			   Just (tc, tys) -> tc
 
 		-- Used for "rough matching"; same idea as for class instances
 	    , fi_tcs   :: [Maybe Name]	-- Top of type args
+		-- INVARIANT: fi_tcs = roughMatchTcs fi_tys
 
 		-- Used for "proper matching"; ditto
 	    , fi_tvs   :: TyVarSet	-- Template tyvars for full match
 	    , fi_tys   :: [Type]	-- Full arg types
+		-- INVARIANT: fi_tvs = tyConTyVars fi_tycon
+		--	      fi_tys = case tyConFamInst_maybe fi_tycon of
+		--			   Just (_, tys) -> tys
 
 	    , fi_tycon :: TyCon		-- Representation tycon
 	    }
@@ -76,14 +82,13 @@ instance Outputable FamInst where
 pprFamInst :: FamInst -> SDoc
 pprFamInst famInst
   = hang (pprFamInstHdr famInst)
-	2 (ptext SLIT("--") <+> (pprDefnLoc (getSrcLoc famInst)))
+	2 (ptext SLIT("--") <+> (pprDefnLoc (getSrcSpan famInst)))
 
 pprFamInstHdr :: FamInst -> SDoc
 pprFamInstHdr (FamInst {fi_fam = fam, fi_tys = tys, fi_tycon = tycon})
   = pprTyConSort <+> pprHead
   where
-    pprHead = parenSymOcc (getOccName fam) (ppr fam) <+> 
-	      sep (map pprParendType tys)
+    pprHead = pprTypeApp (parenSymOcc (getOccName fam) (ppr fam)) tys
     pprTyConSort | isDataTyCon tycon = ptext SLIT("data instance")
 		 | isNewTyCon  tycon = ptext SLIT("newtype instance")
 		 | isSynTyCon  tycon = ptext SLIT("type instance")
@@ -188,61 +193,29 @@ extendFamInstEnv inst_env ins_item@(FamInst {fi_fam = cls_nm, fi_tcs = mb_tcs})
 %*									*
 %************************************************************************
 
-@lookupFamInstEnvExact@ looks up in a @FamInstEnv@ using an exact match.
-This is used when we want the @TyCon@ of a particular family instance (e.g.,
-during deriving classes).
+@lookupFamInstEnv@ looks up in a @FamInstEnv@, using a one-way match.
+Multiple matches are only possible in case of type families (not data
+families), and then, it doesn't matter which match we choose (as the
+instances are guaranteed confluent).
 
-\begin{code}
-{-		NOT NEEDED ANY MORE
-lookupFamInstEnvExact :: (FamInstEnv		-- External package inst-env
-		         ,FamInstEnv)		-- Home-package inst-env
-		      -> TyCon -> [Type]	-- What we are looking for
-	              -> Maybe FamInst
-lookupFamInstEnvExact (pkg_ie, home_ie) fam tys
-  = home_matches `mplus` pkg_matches
-  where
-    rough_tcs    = roughMatchTcs tys
-    all_tvs      = all isNothing rough_tcs
-    home_matches = lookup home_ie 
-    pkg_matches  = lookup pkg_ie  
+We return the matching family instances and the type instance at which it
+matches.  For example, if we lookup 'T [Int]' and have a family instance
 
-    --------------
-    lookup env = case lookupUFM env fam of
-		   Nothing -> Nothing		-- No instances for this class
-		   Just (FamIE insts has_tv_insts)
-		       -- Short cut for common case:
-		       --   The thing we are looking up is of form (C a
-		       --   b c), and the FamIE has no instances of
-		       --   that form, so don't bother to search 
-		     | all_tvs && not has_tv_insts -> Nothing
-		     | otherwise                   -> find insts
-
-    --------------
-    find [] = Nothing
-    find (item@(FamInst { fi_tcs = mb_tcs, fi_tys = tpl_tys }) : rest)
-	-- Fast check for no match, uses the "rough match" fields
-      | instanceCantMatch rough_tcs mb_tcs
-      = find rest
+  data instance T [a] = ..
 
-        -- Proper check
-      | tcEqTypes tpl_tys tys
-      = Just item
+desugared to
 
-        -- No match => try next
-      | otherwise
-      = find rest
--}
-\end{code}
+  data :R42T a = ..
+  coe :Co:R42T a :: T [a] ~ :R42T a
 
-@lookupFamInstEnv@ looks up in a @FamInstEnv@, using a one-way match.
-Multiple matches are only possible in case of type families (not data
-families), and then, it doesn't matter which match we choose (as the
-instances are guaranteed confluent).
+we return the matching instance '(FamInst{.., fi_tycon = :R42T}, Int)'.
 
 \begin{code}
+type FamInstMatch = (FamInst, [Type])           -- Matching type instance
+
 lookupFamInstEnv :: FamInstEnvs
 	         -> TyCon -> [Type]		-- What we are looking for
-	         -> [(TvSubst, FamInst)] 	-- Successful matches
+	         -> [FamInstMatch] 	        -- Successful matches
 lookupFamInstEnv (pkg_ie, home_ie) fam tys
   = home_matches ++ pkg_matches
   where
@@ -272,7 +245,7 @@ lookupFamInstEnv (pkg_ie, home_ie) fam tys
 
         -- Proper check
       | Just subst <- tcMatchTys tpl_tvs tpl_tys tys
-      = (subst, item) : find rest
+      = (item, substTyVars subst (tyConTyVars tycon)) : find rest
 
         -- No match => try next
       | otherwise
@@ -291,7 +264,7 @@ indexed synonyms and we don't want to slow that down by needless unification.
 
 \begin{code}
 lookupFamInstEnvUnify :: (FamInstEnv, FamInstEnv) -> TyCon -> [Type]
-	              -> [(TvSubst, FamInst)]
+	              -> [(FamInstMatch)]
 lookupFamInstEnvUnify (pkg_ie, home_ie) fam tys
   = home_matches ++ pkg_matches
   where
@@ -327,7 +300,9 @@ lookupFamInstEnvUnify (pkg_ie, home_ie) fam tys
 		-- Unification will break badly if the variables overlap
 		-- They shouldn't because we allocate separate uniques for them
         case tcUnifyTys bind_fn tpl_tys tys of
-	    Just subst -> (subst, item) : find rest
+	    Just subst -> let rep_tys = substTyVars subst (tyConTyVars tycon)
+                          in
+                          (item, rep_tys) : find rest
 	    Nothing    -> find rest
 
 -- See explanation at @InstEnv.bind_fn@.