generator.scala

    object Generator {
      def apply[A](head: A)(next: A => A) : Generator[A] = Impl(head, next)
      
      private final case class Impl[A](override val head: A, next: A => A)
      extends Generator[A] {
        protected def underlying = this
      }
    }
    sealed trait Generator[A]
    extends IterableView[A, Generator[A]] with IterableViewLike[A, Generator[A], Generator[A]] {
      protected def next: A => A
      def iterator = Iterator.iterate(head)(next)
      trait Transformed[B] extends Generator[B] // with super[IterableViewLike].Transformed[B]
    }