[Haskell] Composing applicative functors?

Ross Paterson ross at soi.city.ac.uk
Wed Feb 21 19:39:13 EST 2007

[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
> [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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