Scala Map function

ListMap.scala

object ListMap {
  def squareList(xs: List[Int]): List[Int] = xs match { 
    case List() => xs
    case y :: ys => y * y :: squareList(ys)
  } 
  def squareListMap(xs: List[Int]): List[Int] = 
    xs map (x => x * x)
  
  def main(args: Array[String]) {
    println("squarelist for square of (9,13,21) returns : " + squareList(List(9, 13, 21)));
    println("squareListMap for square of (9,13,21) returns : " + squareList(List(9, 13, 21)));
  }
}