Re: Proposal: Add a wrapped applicative type to Data.Monoid

I can definitely see "App" as being overloaded (Application). Good names that I see are "Ap" and "Apply". I think "Ap" is fine. On Tue, Mar 27, 2018, 10:28 AM David Feuer wrote:

I proposed same thing some time ago. The main point of contention was the name. I hope you have better luck!

On Tue, Mar 27, 2018, 10:23 AM Daniel Cartwright wrote:

...

I see this as being generally (as in, to the users of Haskell as a whole) useful:

newtype Ap f a = Ap { getAp :: f a } deriving (Applicative, Eq, Foldable, Functor, Generic, Generic1 ,Monad, Ord, Read, Show, Traversable)

Some hand-written instances: instance (Applicative f, Semigroup a) => Semigroup (Ap f a) where (Ap x) <> (Ap y) = Ap $ liftA2 (<>) x y

instance (Applicative f, Monoid a) => Monoid (Ap f a) where mempty = Ap $ pure mempty _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries