[project @ 1996-04-05 08:26:04 by partain]

[ghc-hetmet.git] / ghc / compiler / utils / MatchEnv.lhs

diff --git a/ghc/compiler/utils/MatchEnv.lhs b/ghc/compiler/utils/MatchEnv.lhs
index 28b8ad2..81271a2 100644 (file)
--- a/ghc/compiler/utils/MatchEnv.lhs
+++ b/ghc/compiler/utils/MatchEnv.lhs
@@ -9,7 +9,7 @@
 
 module MatchEnv (
        MatchEnv, nullMEnv, mkMEnv,
-       lookupMEnv, insertMEnv,
+       isEmptyMEnv, lookupMEnv, insertMEnv,
        mEnvToList
 ) where
 
@@ -36,11 +36,15 @@ match will be the most specific.
 nullMEnv :: MatchEnv a b
 nullMEnv = EmptyME
 
+isEmptyMEnv EmptyME = True
+isEmptyMEnv _      = False
+
 mkMEnv :: [(key, value)] -> MatchEnv key value
+mkMEnv []    = EmptyME
 mkMEnv stuff = ME stuff
 
 mEnvToList :: MatchEnv key value -> [(key, value)]
-mEnvToList EmptyME = []
+mEnvToList EmptyME    = []
 mEnvToList (ME stuff) = stuff
 \end{code}