Re: Functor => Pointed => Applicative => Monad

On 11/29/10 10:30 AM, Stephen Tetley wrote:

On 29 November 2010 13:28, John Smith wrote:

...

fmap = map

This could be part of a legacy module, along with any other eliminated duplicated functions. Historical cruft remains in Haskell far too long; is there no desire for an occasional cleanup?

Speaking personally, I'm quite happy to have both map and (functorial) fmap.

Haskell's intention is to be a "state of the art _functional_ language", so keeping the functional core doesn't seem unwarranted to me. There is the Charity language which was "categorical" first, and "functional" second if people really want a "crystal mountain".

Also, e.g., I'll often use "map" when my specific intention is to restrict a type to lists, whereas I use "fmap" when I intend to be general. Similarly for "concat" vs "join". While it is theoretically valuable to see that one is just a specialization of the other, it is practically valuable to make use of that specialization in order to have our programs convey exactly what we mean (instead of what we /could/ mean). While we really like extensionality, intensionality has its place too. -- Live well, ~wren