Pretty sure cofunctors are functors :p In any case, I think the name “functor” is pretty apt, makes some sense compared to what I’d learned in algebra. Cheers, Vanessa McHale

On Apr 22, 2020, at 4:50 AM, Tony Zorman wrote:

Hi Marc,

On Wed, Apr 22 2020 11:17, Marc Busqué wrote:

...

For instance, a functor can be both covariant and contravariant

Judging from personal experience, "functor" in mathematics always (for a sufficiently small definition of always) refers to a covariant functor. If something is contravariant you usually declare it explicitly. These concepts are rather related though; one may view any contravariant functor F: C -> D as a covariant one, either by F: C^o -> D or by F: C -> D^o.

...

Would `Cofunctor` be a better name for it?

Cofunctor has some ambiguity around it. While it might refer to a contravariant functor it may as well refer to the dual of a functor (which is again a functor).

Cheers, -- Tony Zorman | PGP: 0xc927de8c7dfd57b8 _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.