Re: [Haskell-cafe] Restricted type classes

On Sat, Sep 4, 2010 at 12:34 PM, David Menendez wrote:

On Fri, Sep 3, 2010 at 8:23 AM, John Lato wrote:

...

+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?

Having Pointed is categorically the right thing to do, which is why I argue for its inclusion. Also, I think it would be prudent to avoid a situation with the possibility of turning into a rehash of the Functor/Applicative/Monad mess. Are there any good reasons for not including it? Just because we don't have a use now doesn't mean it might not be useful in the future. John