import Control.Exception

getWord :: IO String
getWord =
  putStrLn "Enter something:" >>
  getLine >>= \name ->
  case name of
    "bad" -> ioError $ userError "bad word detected"
    _     -> return name

getWordWithoutBadWord :: IO String
getWordWithoutBadWord = catch getWord handler
  where handler :: IOError -> IO String
        handler e = return $ "(filtered) - reason: " ++ show e

main :: IO ()
main = getWordWithoutBadWord >>= \name -> putStrLn name