newTyConInstRhs,
-- (Type families)
- tyFamInsts,
+ tyFamInsts, predFamInsts,
-- (Source types)
mkPredTy, mkPredTys, mkFamilyTyConApp,
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}