Putting Contravariant in base sounds like a reasonable thing to do.
It's a pretty basic class.
Deriving Contravariant seems a bit tricky. If Contravariant is in base
and part of the deriving code, what Functor/Contravariant instances do
you derive for e.g. newtype Compose f g a = Compose (f (g a))?
Shachaf
On Sun, Dec 11, 2016 at 8:14 AM, Andrew Martin
The typeclass Contravariant (from the contravariant package) is both useful and fundamental. I would like to see this moved into base. One additional motivating factor is that it would become possible for a DeriveContravariant extension to be written in a future GHC release. I'd love to hear other people's thoughts, even if it's as simple as a yea or nay. Thanks.
-Andrew Martin _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries