I understand the error below, but I'm not really sure what an instance of liftIO would look like for the Identity functor. I guess I'm not all to clear on what an identity functor is. I'm a little fuzzy on what an identity monad is. I understand that id gives the identity of something back pretty well though. Can anyone help? If anyone could help me fix the code below as well as explain the questions I have above it would be a great help. import Control.Monad.Trans.State import Control.Monad.IO.Class type MyState = State Int modAndPrintState :: Int -> MyState () modAndPrintState x = do get >>= \i -> do liftIO . print $ i if even x then put (x + i) else put (i * (x + 1) - x) main = undefined -- Prelude Control.Monad.Trans.State> :r -- [1 of 1] Compiling Main ( blah2.hs, interpreted ) -- blah2.hs:9:5: -- No instance for (MonadIO Data.Functor.Identity.Identity) -- arising from a use of `liftIO' -- Possible fix: -- add an instance declaration for -- (MonadIO Data.Functor.Identity.Identity) -- In the first argument of `(.)', namely `liftIO' -- In the expression: liftIO . print -- In a stmt of a 'do' block: liftIO . print $ i -- Failed, modules loaded: none. Thanks!