X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FFamInstEnv.lhs;h=b8c82f862328f79e1e7a0af7fcfe43cf946002dc;hb=ecdc15ea7813c43a4d84b7c6554a13c06f210a7e;hp=b9276b7cf6ee2ff406969c808deff9ae11ff7a8d;hpb=3548802de235eca280982270463db84910ee3748;p=ghc-hetmet.git

diff --git a/compiler/types/FamInstEnv.lhs b/compiler/types/FamInstEnv.lhs
index b9276b7..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")
@@ -193,10 +198,24 @@ 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 family instances and the type instance at which it
+matches.  For example, if we lookup 'T [Int]' and have a family instance
+
+  data instance T [a] = ..
+
+desugared to
+
+  data :R42T a = ..
+  coe :Co:R42T a :: T [a] ~ :R42T a
+
+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
@@ -226,7 +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
@@ -245,7 +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
@@ -281,7 +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@.