viewducers.scala

trait ViewTransformer[-A,+B] {
  def sequence(in: Iterable[A]) = transform(in.view).to(IterableFactory.toSpecific(in.iterableFactory))
  def transform(v: View[A]): View[B]
  def map[C](f: B => C): ViewTransformer[A,C] = new ViewTransformerImpl[A,C,B](this) {
    override def transform(v: View[A]): View[C] =  prev.transform(v).map(f)
  }
  def flatMap[C](f: B => IterableOnce[C]): ViewTransformer[A,C] = new ViewTransformerImpl[A,C,B](this) {
    override def transform(v: View[A]): View[C] =  prev.transform(v).flatMap(f)
  }
}
object ViewTransformer {
  def id[A] = new ViewTransformer[A,A] {
    def transform(v: View[A]) = v
  }
}
abstract class ViewTransformerImpl[-A,+B,+Interm](val prev: ViewTransformer[A,Interm]) extends ViewTransformer[A,B]