[project @ 2001-01-25 17:09:46 by simonpj]

Add elemSubstEnv

diff --git a/ghc/compiler/basicTypes/VarEnv.lhs b/ghc/compiler/basicTypes/VarEnv.lhs
index 646d5fa..393a384 100644 (file)
--- 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
@@ -93,6 +93,9 @@ 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)