Cats instances for Scalacheck `Gen`?

[armanbilge]

Specifically, to help with this:

weaver-test/docs/scalacheck.md

Lines 46 to 53 in 850a8a6

	// There is only one overload for the `forall` that takes an explicit `Gen` parameter
	// To use multiple `Gen` instances, compose them monadically before passing to `forall`
	test("Multiple Gen form") {
	// Compose into a single `Gen[(Int, Int)]`
	val gen = for {
	a <- Gen.posNum[Int]
	b <- Gen.posNum[Int]
	} yield (a, b)

Which is a reasonable setup IMO. Personally I'm just missing some of the handy combinators for composition. E.g. it would be nice to express that example using .product or .tupled instead of needing the multi-line for ... yield.

There's options like cats-scalacheck but it would be very convenient to be able to do this out-of-the-box.

[Baccata]

So you're suggesting inlining the instances in weaver ? I'm not fundamentally opposed to it