Yeah, it would probably have to have a new name because it does have a different kind than the existing Endo. GEndo was the best I could come up with that didn't sound verbose (GeneralizedEndo, CategoricalEndo) or like it was naming the wrong thing (EndoCategory). I'm not wedded to the name by any means. Note: a type synonym,
type Endo = GEndo (->)
like you mentioned would work, but has the downside that it may require
clients that provided instances for Endo to add TypeSynonymInstances where
they previously hadn't and I'm not sure how folks would feel about that.
-Edward Kmett
On Wed, Jul 8, 2009 at 2:05 PM,
On Wed, 8 Jul 2009, Edward Kmett wrote:
+1 in favor of generalizing Endo in Data.Monoid.
In my monoids library I have a Data.Monoid.Categorical that includes a 'GEndo' generalized endomorphism over an arbitrary category and I would love to be able to remove it.
-Edward Kmett
I was looking for this in your lib, but I didn't find it.
Anyhow, I'm also in favour of generalizing Endo. I was being conservitive with my initial proposal.
Would we still have to pick a new name and then
type Endo a = NewEndoName (->) a
?
In Data.Monoid there is
newtype Endo a = Endo { appEndo :: a -> a }
instance Monoid (Endo a) where mempty = Endo id Endo f `mappend` Endo g = Endo (f . g)
and (->) is an instance of Category, so perhaps we should generalize Endo.
The name EndoCategory seems wrong, as this won't be an instance of Category. Endomorphism? _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries
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