Am Sonntag, 5. Februar 2006 17:36 schrieb Bulat Ziganshin: > [...] > each and every monadic operation is a function!
What do you mean with "monadic operatation"? (>>=), (>>) and return are, of course, functions but an I/O action like getChar is *not* a function. Also a list is not a function but a value of the list monad. > type "IO a" is really "RealWorld -> (RealWorld,a)" This representation is just there to help people understand what I/O is but actually, IO a is a type which is not implementable in ordinary Haskell and therefore cannot be a function. In addition, RealWorld -> (RealWorld,a) as an explanation of what IO a is has its limitations. If we run an I/O action, we aren't just interested in the final state but also in intermediate states. > and the same for any other monad. concept of the monad by itself means > carrying "hidden" state from one monadic operation to the next. That's too specific. A list, for example, doesn't have to do anything with state and [a] is not represented as a function. > [...] Best wishes, Wolfgang _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
