[Haskell] Composing applicative functors?

[Conal Elliott]

I'm still interested in comments composition operators at
http://haskell.org/haskellwiki/TypeComposition.   Now I see that my ":.::"
is what [1] calls "StaticArrow".

Mainly, I'd like to hear thoughts on how to make an arrow out of a functor &
arrow, with the functor on the inside.  My attempt is called "::.:" on the
wiki page.

    newtype ((~>) ::.: f) a b = TT_T {runTT_T :: f a ~> f b}

As mentioned in the comments, my Arrow definition isn't really
satisfactory.  Is there an arrow that corresponds to this sort of
composition?

Thanks,  - Conal

On 3/8/07, Conal Elliott <conal at conal.net> wrote:
>
> I made a first pass at a module of type compositions with some instances
> at http://haskell.org/haskellwiki/TypeComposition and would love to get
> comments & suggestions.
>
> Is there an existing process for library proposals & discussions?
>
> Cheers,  - Conal
>
> On 2/21/07, Ross Paterson < ross at soi.city.ac.uk> wrote:
> >
> > [redirecting to libraries]
> > On Wed, Feb 21, 2007 at 04:23:50PM -0800, Conal Elliott wrote:
> > > Is the composition instance of Control.Applicative defined
> > somewhere?  I see
> > > it in the McBride & Paterson paper [1], but not in the library docs
> > [2].
> > > I'd rather pull it in from a library than (re)define it myself.
> > >
> > > [1] http://www.soi.city.ac.uk/~ross/papers/Applicative.pdf<http://www.soi.city.ac.uk/%7Eross/papers/Applicative.pdf>
> > > [2]
> > > http://www.haskell.org/ghc/docs/latest/html/libraries/base/Control-Applicative.html
> >
> >
> > It's not defined in the libraries.  The type (and the identity functor)
> > should probably go in the module that defines Functor (currently
> > Control.Monad) with a Functor instance, and an Applicative instance
> > in Control.Applicative.
> >
> > _______________________________________________
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> > Libraries at haskell.org
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> >
>
>
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