My training wheels implementation of Sieve of Eratosthenes to generate prime numbers.

 * Find prime numbers using Eratosthenes Sieve.
 * Scala Gods - this is neither functional nor scala except the syntax.
 * Think pseudocode that actually compiles and works.
object EratosthenesSieve extends App {
  val primes = getPrimes(1000)
  println(primes.mkString(" ,"))
  def getPrimes(x: Int) : Seq[Int]= {
    //We use a single dimension array, we will use the index as the number.
    val sieve = new Array[Int](x)
    //we will flip these to 0 as we traverse. Initially, every number is prime.
    for (i <- 0 to sieve.size-1) sieve(i) = 1
    //This is our pivot. We leave sieve(0) and sieve(1) alone. Sieve(2) has number 2 which is our first prime number.
    var pivot = 2
    while(pivot <= (x-1)/pivot){
      //we start with the pivot, and mark all its multiples except itself as non-prime.
      //we do this till we reach the end of the array
      for(i <- 2 to (x-1)/pivot){
        sieve(pivot*i) = 0 //not prime
      //now we find the next pivot which is the next in the array which is 1
      pivot = nextPivot(pivot,sieve)
    //filter our the primes, we use some real scala here, sorry. Kinda tired.
    for(s<-2 to sieve.size-1; if(sieve(s)==1)) yield(s)

  def nextPivot(currentPivot:Int, x:Array[Int]) : Int = {
    //return the next pivot, which is the next index after currentPivot that is 1
    var nextPivot = currentPivot+1
    var done = false
      if(x(nextPivot)==1) done = true
      else nextPivot += 1