Type Contains

Contains.scala

sealed trait TList
case object TNil extends TList
case class <+>[A, B <: TList]() extends TList //some weird symbol for ::

trait Contains[A, TL <: TList]

object Contains extends LowPriorityContains{
  def apply[A, TL <: TList](implicit cnt: Contains[A, TL]) = cnt

  implicit def has[F[_], A, T <: TList] = new Contains[F, F[A] <+> T]{}
  implicit def has[F[_], H, T <: TList](implicit cnt: Contains[F, T]) = new Contains[F, H :: T]{}
}

trait LowPriorityContains{
  implicit def has[A, T <: TList] = new Contains[A, A <+> T]{}
  implicit def recur[A, H, T <: TList](implicit cnt: Contains[A, T]) = new Contains[A, H <+> T]{}
}

//Next question, does it work on higher kinded types? List[_]