findPrimes

findPrimes.scala

def findPrimes(toInt: Int): Seq[Int] = {

def eras(l: Seq[Int]): Seq[Int] = {
  val size = l.size
  val mlist = collection.mutable.IndexedSeq(l:_*)
  
  def crossout(x: Int): Unit = {
    def crossout(xbase: Int, x: Int):Unit = {
      if (x<size) {
        mlist(x) = 0
        crossout(xbase, x+xbase)
      }
      else ()
    }
    crossout(x,x)  
  }

  def eras() : List[Int] = {
    mlist.find(_>0) match {
      case Some(x) =>
        if (x<size) { 
          crossout(x)
          x::eras
        }
        else Nil
      case None => Nil
    }
  }  
  
  if (size<2) 
    Seq[Int]()
  else
    mlist(1) = 0;
    eras
}

if (toInt < 0) 
  Seq[Int]()
else {
  val primes = eras (0 to toInt)
  primes
}

}