shall I have your elaboration on how the implicit function "mk" works?

[epiphyllum]

trait Inner[F]{
type T
}

object Inner{
def apply[F](implicit inner: Inner[F]) = inner

implicit def mk[F[_], A] = new Inner[F[A]]{
type T = A
}
}

[wheaties]

What that is saying is that unless someone specifically defines a Inner for some type A elsewhere, the only type pattern which will match is a single arity type constructor. Does that make sense?

Oh, I should mention, don't get hung up by the letters of the types. So, Option[Int] would have an Inner but BigDecimal would not, List[BigDecimal] would but Map[Int,Double] would not.