On 5 September 2010 03:34, David Menendez <d...@zednenem.com> wrote: > On Fri, Sep 3, 2010 at 8:23 AM, John Lato <jwl...@gmail.com> wrote: >> Do you have a kind * implementation of Foldable? I'd be interested in >> seeing it, because I was unable to create a usable implementation (based >> upon the RMonad scheme) on my last attempt. > > I always figured it would look something like: > > class Foldable f where > type Elem f :: * > foldMap :: Monoid m => (Elem f -> m) -> f -> m > > with the usual definitions for foldr, foldl, etc. > >> +1 for using the proper constraints, and especially for bringing over >> Pointed (and anything else that applies). > > What's the argument for Pointed? Are there many types which are > instances of Pointed but not Applicative? Are there many algorithms > which require Pointed but not Applicative?
Presumably just that it's another possible abstraction. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
