Two improvements to optCoercion

[ghc-hetmet.git] / compiler / types / Type.lhs

diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs
index fd275da..242e603 100644 (file)
--- a/compiler/types/Type.lhs
+++ b/compiler/types/Type.lhs
@@ -123,7 +123,8 @@ module Type (
        emptyTvSubstEnv, emptyTvSubst,
        
        mkTvSubst, mkOpenTvSubst, zipOpenTvSubst, zipTopTvSubst, mkTopTvSubst, notElemTvSubst,
-       getTvSubstEnv, setTvSubstEnv, getTvInScope, extendTvInScope, extendTvInScopeList,
+       getTvSubstEnv, setTvSubstEnv, zapTvSubstEnv, getTvInScope, 
+        extendTvInScope, extendTvInScopeList,
        extendTvSubst, extendTvSubstList, isInScope, composeTvSubst, zipTyEnv,
         isEmptyTvSubst,
 
@@ -1437,6 +1438,9 @@ notElemTvSubst tv (TvSubst _ env) = not (tv `elemVarEnv` env)
 setTvSubstEnv :: TvSubst -> TvSubstEnv -> TvSubst
 setTvSubstEnv (TvSubst in_scope _) env = TvSubst in_scope env
 
+zapTvSubstEnv :: TvSubst -> TvSubst
+zapTvSubstEnv (TvSubst in_scope _) = TvSubst in_scope emptyVarEnv
+
 extendTvInScope :: TvSubst -> Var -> TvSubst
 extendTvInScope (TvSubst in_scope env) var = TvSubst (extendInScopeSet in_scope var) env