[when matching against the empty string, do it directly rather than via a packed string
John Meacham <john@repetae.net>**20061219051353] hunk ./E/FromHs.hs 760
+                    f els (HsPLit (HsString ""),ps) = do
+                        m <- match bs ps err
+                        return $ eCase bv [Alt (litCons { litName = dc_EmptyList, litType = tString }) m] els