gistfile1.scala

object Ishi extends App {

  class Primes {
    val primes: Stream[Long] = 2 #:: primesStartingFrom(3)

    def isPrime(n: Long): Boolean = {
      val limit = math.sqrt(n).ceil.toInt
      !primes.takeWhile(_ < limit).exists(n % _ == 0)
    }

    private def primesStartingFrom(n: Int): Stream[Long] = {
      if (isPrime(n)) {
        n #:: primesStartingFrom(n + 2)
      } else {
        primesStartingFrom(n + 2)
      }
    }
  }

  val primes = new Primes

  Iterator.iterate(3L)(_ + 2).takeWhile(_ < 490L).grouped(2).foreach(is => {
    is.par.foreach(i => {
      println("Checking: " + i)
      if (primes.isPrime(i)) {
        println(i)
      }
    })
  })

}