Compile and Execute Scala Online

object HelloWorld {
   def main(args: Array[String]) {
   //I have a List(1 ,2 ,3 ,4 ,5) and trying to get a sublist: List(3, 4) from it by the following way:
    val list = List(1 ,2 ,3 ,4 ,5)
                  //0, 1, 2, 3, 4
                        //3, 4
    var b = list.splitAt(3)._2
    println(b)
    println(sum(list))
    def sum(xs: List[Int]): Int = xs match {
      case Nil => 0
      case _ :: tail if tail.length==0 => 0 // size 1
      case _ :: tail if tail.length==2 => tail(1) //size 2
      case _ :: tail if tail.length>2 => tail(0) + tail(1) + sum(tail.splitAt(3)._2)
    }
   }
}