Given the parameter includes the type: def test(v: Int < Env[Int]
Can you try invoking it like: test(Envs.get)? not that this is particularly safe...

yep! That works too. Why do you say it could be unsafe?

Type unsafe 🙂 - inference could change depending on how the function is defined. Obviously not a problem with Kyo's encoding.

It's likely not a concern for most users, as they should rarely define functions where the result type is generic.

eg

type Pending = Envs[Float] & Envs[Double]
def myFunc[T](effect: T < Pending) = effect.map(_ / 2)

val result: ??? = myFunc(Envs.get)

Determinism in the Scala compiler is generally good, but I generally prefer not to take changes.

I tested this and it's actually unsafe as you suspected. It's not much about the method inference but Scala infers a type intersection as the environment type, which fails when handling the effect. I think we'll need to add a constraint similar to Flat to validate that the type is not an intersection. Another option is using Tag to check types during handling but that's too expensive.

I added a couple pending tests because I think this doesn't seem a blocker.