X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FFamInstEnv.lhs;h=89fd193914b502f1ce3ff7b6a0e8ad7cf5c40be7;hb=9a0100000f820caf09e2e8f5304a6e008a614729;hp=50c827f2223f73368c28aede19c1f39ac6f59e91;hpb=027e6be20af2e59e2ec720042d23ef06d9a7d4c1;p=ghc-hetmet.git

diff --git a/compiler/types/FamInstEnv.lhs b/compiler/types/FamInstEnv.lhs
index 50c827f..89fd193 100644
--- a/compiler/types/FamInstEnv.lhs
+++ b/compiler/types/FamInstEnv.lhs
@@ -36,8 +36,6 @@ import Outputable
 import Maybes
 import Util
 import FastString
-
-import Maybe
 \end{code}
 
 
@@ -94,10 +92,11 @@ pprFamInstHdr (FamInst {fi_fam = fam, fi_tys = tys, fi_tycon = tycon})
   = pprTyConSort <+> pprHead
   where
     pprHead = pprTypeApp fam tys
-    pprTyConSort | isDataTyCon tycon = ptext (sLit "data instance")
-		 | isNewTyCon  tycon = ptext (sLit "newtype instance")
-		 | isSynTyCon  tycon = ptext (sLit "type instance")
-		 | otherwise	     = panic "FamInstEnv.pprFamInstHdr"
+    pprTyConSort | isDataTyCon     tycon = ptext (sLit "data instance")
+		 | isNewTyCon      tycon = ptext (sLit "newtype instance")
+		 | isSynTyCon      tycon = ptext (sLit "type instance")
+		 | isAbstractTyCon tycon = ptext (sLit "data instance")
+		 | otherwise	         = panic "FamInstEnv.pprFamInstHdr"
 
 pprFamInsts :: [FamInst] -> SDoc
 pprFamInsts finsts = vcat (map pprFamInst finsts)
@@ -228,7 +227,7 @@ lookupFamInstEnv
     -> [FamInstMatch] 	        -- Successful matches
 
 lookupFamInstEnv
-   = lookup_fam_inst_env match
+   = lookup_fam_inst_env match True
    where
      match _ tpl_tvs tpl_tys tys = tcMatchTys tpl_tvs tpl_tys tys
 
@@ -245,7 +244,7 @@ lookupFamInstEnvConflicts
 -- unique supply to hand
 
 lookupFamInstEnvConflicts envs fam_inst skol_tvs
-  = lookup_fam_inst_env my_unify envs fam tys'
+  = lookup_fam_inst_env my_unify False envs fam tys'
   where
     inst_tycon = famInstTyCon fam_inst
     (fam, tys) = expectJust "FamInstEnv.lookuFamInstEnvConflicts"
@@ -275,12 +274,13 @@ lookupFamInstEnvConflicts envs fam_inst skol_tvs
       | otherwise      = not (old_rhs `tcEqType` new_rhs)
       where
         old_tycon = famInstTyCon old_fam_inst
-        old_rhs   = mkTyConApp old_tycon (substTyVars subst (tyConTyVars old_tycon))
+        old_tvs   = tyConTyVars old_tycon
+        old_rhs   = mkTyConApp old_tycon  (substTyVars subst old_tvs)
         new_rhs   = mkTyConApp inst_tycon (substTyVars subst skol_tvs)
 \end{code}
 
 While @lookupFamInstEnv@ uses a one-way match, the next function
-@lookupFamInstEnvUnify@ uses two-way matching (ie, unification).  This is
+@lookupFamInstEnvConflicts@ uses two-way matching (ie, unification).  This is
 needed to check for overlapping instances.
 
 For class instances, these two variants of lookup are combined into one
@@ -297,12 +297,16 @@ type MatchFun =  FamInst		-- The FamInst template
 	      -> [Type]			-- Target to match against
 	      -> Maybe TvSubst
 
+type OneSidedMatch = Bool     -- Are optimisations that are only valid for
+                              -- one sided matches allowed?
+
 lookup_fam_inst_env 	      -- The worker, local to this module
     :: MatchFun
+    -> OneSidedMatch
     -> FamInstEnvs
     -> TyCon -> [Type]		-- What we are looking for
     -> [FamInstMatch] 	        -- Successful matches
-lookup_fam_inst_env match_fun (pkg_ie, home_ie) fam tys
+lookup_fam_inst_env match_fun one_sided (pkg_ie, home_ie) fam tys
   | not (isOpenTyCon fam) 
   = []
   | otherwise
@@ -323,7 +327,7 @@ lookup_fam_inst_env match_fun (pkg_ie, home_ie) fam tys
 
     --------------
     rough_tcs = roughMatchTcs match_tys
-    all_tvs   = all isNothing rough_tcs
+    all_tvs   = all isNothing rough_tcs && one_sided
 
     --------------
     lookup env = case lookupUFM env fam of