Ondra Pelech

Hi @soujiro32167 would you like to continue working on this?

What laws apply for Foldable?

That would make me thing that `Foldable` is not as much an actual Type class, but more like a "shape" (we talked about Shapes [here](https://github.com/zio/zio-prelude/pull/351))

Although there are some laws in the [Haskell definition](https://hackage.haskell.org/package/base-4.14.1.0/docs/Data-Foldable.html) > ```haskell > foldr f z t = appEndo (foldMap (Endo . f) t ) z > > foldl f z...

fair enough

@nartamonov yeah... I'm also beginning to think that _not_ using Kind projector is causing more harm than benefit... If there would be an agreement to change the codebase over to...

@lemastero wholeheartedly agree! Sadly, we use variance pervasively, but Dotty doesn't support variance annotations (like `+*`, `-*`) yet :crying_cat_face: https://github.com/lampepfl/dotty/issues/7139#issuecomment-565468066

@adamgfraser @neko-kai Actually, I think that now it is a good time to switch to the nice "kind-projector" syntax for type lambdas. It's supported natively by [Scala 3.0.0](https://scalacenter.github.io/scala-3-migration-guide/docs/tutorials/kind-projector.html) and [now...

I actually tried that, but I found the Lawful/Laws/... from ZIO Test insufficient :disappointed: We would need in ZIO Test something like this ```scala package object laws { object LawfulF...

ticket in ZIO to implement this: https://github.com/zio/zio/issues/4211