Variation on sample program of SftI Ex 22.5, for future reference!

gistfile1.scala

import scala.util.continuations._

object Main extends App {
  val a = "Mary was a little lamb".split(" ")

  type Next = (Boolean => String)
  var next: Next = null
  val firstResultOfShiftBlock = reset {
    var i = 0
    while (i < a.length) {
      val whateverWasPassedToNext = shift { restOfComputationWhenShiftCalled: Next =>
        val res = if (next == null) "This first result is returned by reset."
                  else a(i) // returned by next
        next = restOfComputationWhenShiftCalled
        res
      }
      if (whateverWasPassedToNext == true) i += 1
    }
    "empty"
  }

  println(next(false)) // Mary: don't increment first time round
  println(next(true))  // was
  println(next(true))  // a
  println(next(false)) // a: didn't increment
  println(next(true))  // little
  println(next(true))  // lamb
  println(next(true))  // empty: shift not encountered so get value of reset block
  println(next(true))  // empty: next unchanged!
}