Future instances not in implicit scope

[mrdziuban]

Importing cats.instances.future._ is still required to summon typeclass instances for scala.concurrent.Future, e.g.

import cats.Applicative
import scala.concurrent.Future
import scala.concurrent.ExecutionContext.Implicits.global

Applicative[Future]
// Could not find an instance of Applicative for scala.concurrent.Future

import cats.instances.future._

Applicative[Future]
// cats.Applicative[concurrent.Future] = cats.instances.FutureInstances$$anon$1@479111ba

This was the only cats.instances import I needed to keep around when upgrading a large codebase that strictly uses a la carte imports from v2.1.1 to v2.2.0-RC2.

[LukaJCB]

Thanks for bringing this up! Will have a look soon

[travisbrown]

I believe there was some discussion about this somewhere, and that excluding them was a design decision, but I don't remember the details, and I'm not committed to either including or excluding them from implicit scope.

[barambani]

This #2334 may or may not be what @travisbrown is referring to, but I'm adding it here for reference as that discussion is still open and marked for milestone 3.0

[barambani]

Referencing relevant discussion here #3566 (comment)