Contravariant Functor?

[rjmk]

Copied from fantasyland/static-land#15

Would [fantasyland] be interested in a contravariant functor added to the spec?

It would have a method contramap :: Contravariant f => (a -> b, f b) -> f a. It would become a dependency to profunctor. The laws are pretty much the same as for functor, but with a flip on the functions in composition

Happy to make a PR for [people] to look over

[SimonRichardson]

👍

On Sun, 21 Aug 2016, 17:28 Rafe, [email protected] wrote:

Copied from fantasyland/static-land#15
fantasyland/static-land#15

Would [fantasyland] be interested in a contravariant functor added to the
spec?

It would have a method contramap :: Contravariant f => (a -> b, f b) -> f
a. It would become a dependency to profunctor. The laws are pretty much the
same as for functor, but with a flip on the functions in composition

Happy to make a PR for [people] to look over

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[rpominov]

Probably one of reasons why this didn't happen from the beginning is that we didn't want to claim another name for FL in people's methods namespaces. If that was the case, then this is another argument for #146 .

Edit: we had similar issue with almost every algebra: chain/join, ap/lift, traverse/sequence etc. If we won't have to think about cluttering namespaces we can easily have all methods that we find useful. I mean why don't have both chain and join etc.

[SimonRichardson]

Closing this as the discussions are now in the PR. Reopen if you think otherwise.