diff options
Diffstat (limited to 'ghc/compiler/utils/MatchEnv.lhs')
| -rw-r--r-- | ghc/compiler/utils/MatchEnv.lhs | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/ghc/compiler/utils/MatchEnv.lhs b/ghc/compiler/utils/MatchEnv.lhs index 81271a2982..6c09616e29 100644 --- 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} |