[Haskell-cafe] Applicative banana brackets
hesselink at gmail.com
Mon Dec 14 15:10:34 UTC 2015
Every Arrow is a Functor through:
fmapA :: Arrow arr => (a -> b) -> arr i a -> arr i b
fmapA f a = arr f . a
On 14 December 2015 at 15:53, Kim-Ee Yeoh <ky3 at atamo.com> wrote:
> On Mon, Dec 14, 2015 at 9:38 PM, martin <monkleyon at googlemail.com> wrote:
>> 2) Every arrow a b c is an applicative (a b) c, because comma = (&&&).
>> Conversely, every applicative that is polymorphic over some "internal"
>> variable is automatically an arrow, through (&&&) = comma.
> Where is the proof that (a b) is a Functor?
> Recall that the class method arr -- the closest kin to fmap -- has the type:
> (b -> c) -> a b c.
> -- Kim-Ee
> Haskell-Cafe mailing list
> Haskell-Cafe at haskell.org
More information about the Haskell-Cafe