names, modules, types

Fergus Henderson
Thu, 8 Feb 2001 22:59:44 +1100

On 07-Feb-2001, Marcin 'Qrczak' Kowalczyk <> wrote:
> So why is fmap separate now? Probably because having too much
> overloading causes ambiguities.

Perhaps.  But I think there may be other reasons too.

Having fmap separate is useful for beginners and for teaching,
because you can describe `map' without having to talk about type classes.
Also, it is possible that the error messages that you get when you
make a mistake using `fmap' might be harder to understand.

The reasoning here is similar to the reasons that Haskell 98 has list
comprehensions rather than monad comprehensions.

Fergus Henderson <>  |  "I have always known that the pursuit
                                    |  of excellence is a lethal habit"
WWW: <>  |     -- the last words of T. S. Garp.