Kind polymorphic type cannot must take parameters

[nicolasstucki]

Given that we can write

type K0[T] = T
val a: K0[Int] = 1

type K1[T[_]] = T
val b: K1[List][Int] = Nil

We could try abstract this type over kind with

type K[T <: AnyKind] = T
val a: K[Int] = 1
val b: K[List][Int] = Nil

Though this one currently fails with

-- [E056] Syntax Error ----------------------------
9 |  val a: K[Int] = 1
  |         ^^^^^^
  |         Missing type parameter for Test.K[Int]
-- [E056] Syntax Error ---------------------------
12 |  val b: K[List][Int] = Nil
   |         ^^^^^^^^^^^^
   |         Missing type parameter for Test.K[List][Int]

There is a potential usecase in #6082 for the internal encoding of quoted.Type splices.

[nicolasstucki]

@odersky @milessabin is this pattern supposed to be supported by kind polymorphism?