err :: Int -> String -> IO a
err exitCode msg = do
  name <- getProgName
  UTF8.hPutStrLn stderr $ name ++ ": " ++ msg
  exitWith $ ExitFailure exitCode
  return undefined
err :: Int -> String -> IO a
err exitCode msg = do
  name <- getProgName
  UTF8.hPutStrLn stderr $ name ++ ": " ++ msg
  exitWith $ ExitFailure exitCode
  return undefined
err exitCode msg = do
  name <- getProgName
  UTF8.hPutStrLn stderr $ name ++ ": " ++ msg
  exitWith $ ExitFailure exitCode
  return undefined