Hello, this is my first post to the list. I am learning Haskell and I think I understand monads (well, that doesn't mean that I actually understand them :-) ) Nevertheless, I would like to check something with you. My question is: how do you know in which monad you are computing at a given time? What I mean is that, when dealing with more than a monad at the same time (Maybe, List, IO come to my mind) if I understand correctly you have to lift values back and forth from a monad to the other. How do you "keep" track of the monad you are in a given time? I think that the type system will help to resolve to the relevant function (eg, thinking to liftM signature, liftM :: (Monad m) => (a1 -> r) -> m a1 -> m r But doesn't ever happen that poor liftM be confused? and do poor haskell programmers never feel the need to explicitly state to which monad they "wish to lift" ? I hope it's not a too silly question. If so, please point me to the relevant resouces (Are monad transformers relevant to my issue?) Thanks in advance, Francesco