Roland's Generator

generator.scala

import scala.util.continuations._
import scala.util.Random

class Generator[+T](f : () => T) {
  def apply() : T @cps[Generator[Any]] = shift { this flatMap _ }
  def generate(n : Int) : IndexedSeq[T] = 0 to n map (x => get)
  def get = f()
  def flatMap[TT](ff : T => Generator[TT]) = new Generator( () => ff(get).get )
  def map[TT](ff : T => TT) = new Generator( () => ff(get) )
}

object Generator {
  def apply[T](body : => T @cps[Generator[T]]) : Generator[T] = reset {
    val x = body
    new Generator[T]( () => x )
  }
}

val genInt = new Generator( () => Random.nextInt )
val genBool = new Generator( () => Random.nextBoolean )

case class A(x : Int, b : Boolean)
val genA = Generator( A(genInt(), genBool()) )

genA generate 10 foreach println