[Haskell-beginners] Re: The Applicative instance for ((->) a)

[Heinrich Apfelmus]

Ian Duncan wrote:
> Hey folks, I understand most of what is going on with the applicative
> class, but I can't figure out why this instance is useful:
> "instance Applicative ((->) a) where..."
> 
> Can anyone offer some intuition into how this is could be used?

As hinted to in the paper on applicative functors,

    Applicative programming with effects
    Conor McBride, Ross Paterson.
    http://strictlypositive.org/IdiomLite.pdf

the instance functors are the S and K combinators.

    http://en.wikipedia.org/wiki/SKI_combinator_calculus


Regards,
apfelmus

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