[Haskell-cafe] Higher order functor package?

[Sergey Vinokurov]

Hi Clinton,

Sorry for late reply, but just for the sake of completeness the
compdata package defines just the functor you mentioned
http://hackage.haskell.org/package/compdata-0.11/docs/Data-Comp-Multi-HFunctor.html#t:HFunctor.

Regards,
Sergey

On Tue, Jul 11, 2017 at 9:18 AM, Clinton Mead <clintonmead at gmail.com> wrote:
> Hi All
>
> Thanks for all your help.
>
> I've actually picked up Mario's rank2classes package as it seems like I need
> a little but more power than Functors, as I want things like `liftA2` for
> example.
>
> I've pushed across a very simple pull request to you Mario that simply adds
> "PolyKinds" to your list of language extensions. This automatically this
> generalises the kinds your Functor and Apply accept (and perhaps others) as
> I'm quantifying not over * but over a data kind type. No other changes are
> needed.
>
> Clinton
>
> On Sat, Jul 8, 2017 at 5:57 AM, Mario Blažević <mblazevic at stilo.com> wrote:
>>
>> On 2017-07-07 12:48 AM, Clinton Mead wrote:
>>>
>>> Consider the illustrative code below:
>>> ...
>>>     class MyFunctor f where
>>>        myFmap :: (forall a. t a -> u a) -> f t -> f u
>>> ...
>>>
>>>
>>> Basically this is a sort of "higher order" functor, but I can't seem to
>>> fit it into an ordinary functor.
>>>
>>> But it seems like I'm reinventing the wheel, as my code is suspiciously
>>> like `Functor` but only slightly different.
>>>
>>> Has this sort of class already been created and if so what package is it
>>> in?
>>
>>
>> Yes, I have recently created rank2classes package:
>>
>>    http://hackage.haskell.org/package/rank2classes
>>
>>         Apart from the mirror-universe Functor class, the package exports
>> the Applicative, Foldable, Traversable, Applicative, and Distributive
>> classes, as well as some Template Hashell to derive some of their instances
>> automatically.
>>
>>
>>
>>
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