From: Manuel M T Chakravarty <chak@cse.unsw.edu.au>
Date: Thu, 9 Oct 2008 06:14:35 +0000 (+0000)
Subject: Cover PredTy case in Type.tyFamInsts
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=1ae354e107715a9e3fd4e2d67b61f868c090e4ae;p=ghc-hetmet.git

Cover PredTy case in Type.tyFamInsts

  MERGE TO 6.10
---

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}