X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FbasicTypes%2FVarEnv.lhs;h=d219fe5508cc0de385eac3c6a4312c8fb6f9d5ef;hb=b2a9c48ee5593cda05748c2cd261897392c7152d;hp=646d5fa1d713ece9ea8fedb2b73e2b5cf6c66bca;hpb=d2cca44eae15bbbd3b86889448e796bc785dfa52;p=ghc-hetmet.git

diff --git a/ghc/compiler/basicTypes/VarEnv.lhs b/ghc/compiler/basicTypes/VarEnv.lhs
index 646d5fa..d219fe5 100644
--- a/ghc/compiler/basicTypes/VarEnv.lhs
+++ b/ghc/compiler/basicTypes/VarEnv.lhs
@@ -21,7 +21,7 @@ module VarEnv (
 
 	-- SubstEnvs
 	SubstEnv, TyVarSubstEnv, SubstResult(..),
-	emptySubstEnv, substEnvEnv,
+	emptySubstEnv, substEnvEnv, elemSubstEnv,
 	mkSubstEnv, lookupSubstEnv, extendSubstEnv, extendSubstEnvList,
 	delSubstEnv, delSubstEnvList, noTypeSubst, isEmptySubstEnv
     ) where
@@ -50,6 +50,8 @@ When tidying up print names, we keep a mapping of in-scope occ-names
 
 \begin{code}
 type TidyEnv = (TidyOccEnv, VarEnv Var)
+
+emptyTidyEnv :: TidyEnv
 emptyTidyEnv = (emptyTidyOccEnv, emptyVarEnv)
 \end{code}
 
@@ -93,6 +95,9 @@ isEmptySubstEnv (SE s _) = isEmptyVarEnv s
 lookupSubstEnv :: SubstEnv -> Var -> Maybe SubstResult
 lookupSubstEnv (SE s _) v = lookupVarEnv s v
 
+elemSubstEnv :: Var -> SubstEnv -> Bool
+elemSubstEnv v (SE s _) = elemVarEnv v s
+
 extendSubstEnv :: SubstEnv -> Var -> SubstResult -> SubstEnv
 extendSubstEnv (SE s nt) v r = SE (extendVarEnv s v r) (noTys r nt)