Scalaで素数判定

PrimeNum.scala

import scala.math.sqrt

object PrimeNum {

  def main(args:Array[String]) {
    val num:Long = args(0).toLong

    if(isPrime(num)) println(num + " is Prime Number.")
    else println(num + " is NOT Prime Number.")
  }

  def isPrime(num:Long):Boolean = {
    if (num == 1 || num%2==0) {
      false
    } else {
      (3L to sqrt(num).toLong).filter(
        n => n%2 != 0
      ).foreach { e =>
        if(num%e == 0) return false
      }
      true
    }
  }