Hello, the following error is slightly confusing: ghc --show-iface ghc-6.0.1: unrecognised flag: --show-iface Usage: For basic information, try the `--help' option. ghc --show-iface Unify.hi __interface "Main" Unify 1 where __export Unify Unifiable{mgu} match mguType varBind; ... A hint in the right direction would be more convenient :-) Maybe in /ghc/compiler/main/DriverUtil.hs a function unknownFlagErrUsage :: String->String -> a unknownFlagErrUsage f specusage = throwDyn (UsageError ("unrecognised flag: " ++ f ++ "\n" ++ "hint: " ++ specusage)) and changing processOneArg from DriverFlags.hs HasArg fio -> if rest /= "" then fio rest >> return args else case args of [] -> unknownFlagErrUsage dash_arg "argument for flag expected" (arg1:args1) -> fio arg1 >> return args1 Would this be ok? Regards, Steffen