suggestions

[jdegoes]

I was going to create this. :)

Can I suggest changing the name of the class to IFunctor, and the name of the map function to imap? The other name people use for this is XFunctor, xmap, etc., but personally I prefer IFunctor / imap.

[garyb]

Good call on the imap yep, and I should probably have mentioned something along the lines of "also known as an exponential functor" in the docs.

As for IFunctor, I can see why, as Invariant is a bit vague perhaps, but should we be reconsidering the name of Contravariant as well then?

[jdegoes]

I'd prefer Contravariant be ContraFunctor or some such. There are an infinitely many things which are invariant and contravariant, and no particular reason why covariant functors should be the only ones to get Functor in the name somewhere.

Just my 2 cents, of course.

[LiamGoodacre]

Closing as this looks like a stale issue. I don't see much point in renaming now, Data.Functor.Invariant seems appropriate enough. Please reopen otherwise.