You don't normally call x::Int a computation of an Int because there's nothing that distinguishes the value of the x from what it was before you computed it. So I prefer to regard x as a value (in a domain, of course). But for x :: (Monad m) => m Int there is something else happening, so the word computation makes sense. This is just the terminology people use, not an absolute truth, so you're free to think it's wrong. :) BTW, if you regard non-termination as an effect then even x :: Int is a computation.
-- Lennart On 8/14/07, Dan Piponi <[EMAIL PROTECTED]> wrote: > > On 8/14/07, Jeff Polakow <[EMAIL PROTECTED]> wrote: > > One general intuition about monads is that they represent computations > > rather than simple (already computed) values: > > > x :: Int -- x is an Int > > x :: Monad m => m Int -- x is a computation of an Int > > What's a "computation"? It seems to me that in a lazy language, x::Int > represents a computation of an int, not an "already computed" value. > x::[Int] is a computation that returns multiple values. x::(Int,Int) > is a computation that returns a pair of values. x::() is a computation > that returns nothing. x::Map a b is a computation that gives a way to > associate values of type a with values of type b. Some of these are > monads, some are not. What's the difference between them? Why are you > calling certain values "computations"? > -- > Dan > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
