[Haskell-cafe] Restricted type classes

John Lato jwlato at gmail.com
Sun Sep 5 08:40:22 EDT 2010

On Sat, Sep 4, 2010 at 12:34 PM, David Menendez <dave at zednenem.com> wrote:

> On Fri, Sep 3, 2010 at 8:23 AM, John Lato <jwlato at gmail.com> 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.

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