X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FType.lhs;h=cf38146eb10d59b2c7b16691d72fdd35dba5fab0;hb=1ae354e107715a9e3fd4e2d67b61f868c090e4ae;hp=07e61daf0008c079462ff08b333022bc1946a73b;hpb=32a5c61dc1df5e12aaf1f21e5928fbb261d62043;p=ghc-hetmet.git

diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs
index 07e61da..cf38146 100644
--- a/compiler/types/Type.lhs
+++ b/compiler/types/Type.lhs
@@ -44,7 +44,7 @@ module Type (
 	newTyConInstRhs,
 	
 	-- (Type families)
-        tyFamInsts,
+        tyFamInsts, predFamInsts,
 
         -- (Source types)
         mkPredTy, mkPredTys, mkFamilyTyConApp,
@@ -887,6 +887,14 @@ tyFamInsts (TyConApp tc tys)
 tyFamInsts (FunTy ty1 ty2)      = tyFamInsts ty1 ++ tyFamInsts ty2
 tyFamInsts (AppTy ty1 ty2)      = tyFamInsts ty1 ++ tyFamInsts ty2
 tyFamInsts (ForAllTy _ ty)      = tyFamInsts ty
+tyFamInsts (PredTy pty)         = predFamInsts pty
+
+-- | Finds type family instances occuring in a predicate type after expanding 
+-- synonyms.
+predFamInsts :: PredType -> [(TyCon, [Type])]
+predFamInsts (ClassP _cla tys) = concat (map tyFamInsts tys)
+predFamInsts (IParam _ ty)     = tyFamInsts ty
+predFamInsts (EqPred ty1 ty2)  = tyFamInsts ty1 ++ tyFamInsts ty2
 \end{code}