[Haskell-cafe] How to "instance MonadIO Identity"?

Hi, From another thread in this list, I got code as:

instance MonadIO Identity where liftIO = id Well, it does not work for me as: Message.hs:22:12: Couldn't match expected type `Identity a' with actual type `IO a' Expected type: IO a -> Identity a Actual type: IO a -> IO a In the expression: id In an equation for `liftIO': liftIO = id -- 竹密岂妨流水过 山高哪阻野云飞