wheaties

trait IsNotFuture[+F]

object IsNotFuture{
  def apply[F](implicit isf: IsNotFuture[F]) = isf

  implicit def mkFuture[A] = new IsNotFuture[Future[A]] {}
  implicit object isf extends IsNotFuture[Any] {}
}

//No need for a dependent type. All you need is the implicit ambiguity.

wheaties

trait Change[+A]{
  def map[B](f: A => B): Change[B]
  def flatMap[B](f: A => Change[B]): Change[B]
  def foreach(f: A => Unit): Unit
  def filter(pred: A => Boolean): Change[A]
}

case class Reversible[+A](value: A, undo: List[Undo]) extends Change[A]{
  def map[B](f: A => B) = Reversible(f(value), undo)
  def flatMap[B](f: A => Change[B]) = f(value) match{