On 06/01/11 04:58, Isaac Dupree wrote: > Tony, you're missing the point... Alexey isn't making a complete patch > to GHC/base libraries, just a hacky-looking demonstration. Alexey is > saying that in a class hierarchy (such as if Functor => Monad were a > hierarchy, or for that matter "XFunctor"=>"XMonad" or Eq => Ord), it > is still possible to define the superclass functions (fmap) in terms > of the subclass functions (return and >>=) (such as writing a functor > instance in which "fmap f m = m >>= (return . f)"). This has always > been true in Haskell, it just might not have been obvious. > > _______________________________________________ > Haskell-prime mailing list > Haskell-prime@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-prime Oh right sorry. I thought a stronger point was being made.
Then perhaps it's also worth pointing out that (<*>) can be written using (>>=) and return: f <*> a = f >>= \ff -> a >>= \aa -> return (ff aa) -- Tony Morris http://tmorris.net/ _______________________________________________ Haskell-prime mailing list Haskell-prime@haskell.org http://www.haskell.org/mailman/listinfo/haskell-prime
