Re: map and fmap

On 8/28/06, John Hughes wrote:

As for an example of fmap causing trouble, recall the code I posted last week sometime:

class Foldable f where fold :: (a -> a -> a) -> a -> f a -> a

I'd call this a case of "Foldable" causing trouble. :) Fold is somewhat specific to the structure of the underlying collection (hence the numerous fold* functions), map is not. -- Taral "You can't prove anything." -- Gödel's Incompetence Theorem