unfold in Scala

unfoldScala

    final class Unfoldable[A](a : A){
	    def unfold[B, This, That](f: A => Option[(B, A)])(implicit cb: CanBuildFrom[This, B, That]): That = {
	      val builder = cb()
	      @tailrec def unfolding(a: A) : That = {
	        f(a) match {
	          case Some((e, next)) =>
	            builder += e
	            unfolding(next)
	          case None =>
	            builder.result()
	        }
	      }
	      unfolding(a)
	    }
    } 

    implicit def toUnfoldable[A](a: A) = new Unfoldable (a)