A Functional Prime Number Generator In Scala

primes.scala

  def primes: Stream[Long] = 2 #:: prime3

  // performance: avoid redundant divide by two, so this starts at 3
  private val prime3: Stream[Long] = {
    def next(i: Long): Stream[Long] =
      if (prime(i))
        i #:: next(i + 2)
      else
        next(i + 2) // tail
    3 #:: next(5)
  }
  
    private def prime(i: Long) =
    prime3 takeWhile (math.sqrt(i).>= _) forall { i % _ != 0 }