[project @ 1997-03-14 07:52:06 by simonpj]

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

diff --git a/ghc/compiler/utils/MatchEnv.lhs b/ghc/compiler/utils/MatchEnv.lhs
index 81271a2..6c09616 100644 (file)
--- a/ghc/compiler/utils/MatchEnv.lhs
+++ b/ghc/compiler/utils/MatchEnv.lhs
@@ -95,22 +95,22 @@ insertMEnv match_fn (ME alist) key value
     -- that point.
 
     insert [] = returnMaB (ME [(key, value)])
-    insert ((t,v) : rest)
+    insert ls@(r@(t,v) : rest)
       = case (match_fn t key) of
          Nothing ->
            -- New key is not an instance of this existing one, so
            -- continue down the list.
            insert rest                 `thenMaB` \ (ME rest') ->
-           returnMaB (ME((t,v):rest'))
+           returnMaB (ME(r:rest'))
 
          Just match_info ->
            -- New key *is* an instance of the old one, so check the
            -- other way round in case of identity.
 
            case (match_fn key t) of
-             Just _  -> failMaB (t,v)
+             Just _  -> failMaB r
                         -- Oops; overlap
 
-             Nothing -> returnMaB (ME ((key,value):(t,v):rest))
+             Nothing -> returnMaB (ME ((key,value):ls))
                         -- All ok; insert here
 \end{code}