Kind-polymorphic Any and Nothing

kind-polymorphism.scala

scala> import scala.language.higherKinds
import scala.language.higherKinds

scala> def f[C[_], E]: List[C[E]] = Nil
f: [C[_], E]=> List[C[E]]

scala> f[List, Int]
res0: List[List[Int]] = List()

scala> f[Any, Int]
res1: List[Any] = List()

scala> f[Nothing, Int]
res2: List[Nothing] = List()

scala> f[Int, Int]
<console>:14: error: Int takes no type parameters, expected: one
       f[Int, Int]
         ^

scala> :kind -v List
List's kind is F[+A]
* -(+)-> *
This is a type constructor: a 1st-order-kinded type.

scala> :kind -v Any
Any's kind is A
*
This is a proper type.

scala> :kind -v Nothing
Nothing's kind is A
*
This is a proper type.

scala> :kind -v Int
Int's kind is A
*
This is a proper type.