oom-ing recursion

ok.scala

import java.util.concurrent.atomic.AtomicReference

object ok {

  @scala.annotation.tailrec
  final def filter[A](s: Stream[A], f: A => Boolean): Stream[A] = 
    s match {
      case hd #:: tl =>
       val tailRef = new AtomicReference(tl)
       if (f(hd)) hd #:: filterHelp(tailRef, f) 
       else filter(tl, f)

      case _ => Stream.empty
    }

  final def filterHelp[A](sr: AtomicReference[Stream[A]], f: A => Boolean) =
    filter(sr.getAndSet(null), f)

  val big = 100 * 1000 * 1000

  def s1 = Stream.range(1, big)

  def main(args: Array[String]) {
    println("start")
    var cnt = 0
    filter(s1, (x: Int) => x == 1) foreach { _ => cnt += 1 }
    println(cnt)
  }

}

oom.scala

object oom extends App {

  @scala.annotation.tailrec
  def filter[A](s: Stream[A], f: A => Boolean): Stream[A] = 
    s match {
      case hd #:: tl =>
       if (f(hd)) hd #:: filterHelp(tl, f) 
       else filter(tl, f)

      case _ => Stream.empty
    }

  def filterHelp[A](s: Stream[A], f: A => Boolean) =
    filter(s, f)

  val big = 10000000

  def s1 = Stream.range(1, big)

  println("start")
  val streamSum = filter(s1, (x: Int) => x == 1).sum
  println("stop")

}