RPN in scala

RPN.scala

import scala.collection.mutable.ListBuffer

object Main extends App {

  def getOperator(s: String): Option[((Int, Int) => Int)] = {
    s match {
      case "+" => Some(_+_)
      case "-" => Some(_-_)
      case "/" => Some(_/_)
      case "*" => Some(_*_)
      case _ => None
    }
  }

  val finalStack = args.foldLeft(List[Int]()) { (stack, token) =>
    val mutableStack = stack.to[ListBuffer]
    val i = getOperator(token) match {
      case Some(operator) =>
        val rhs = mutableStack.remove(0)
        val lhs = mutableStack.remove(0)
        operator.apply(lhs, rhs)
      case None => token.toInt
    }

    mutableStack.insert(0, i)
    mutableStack.toList
  }

  print(finalStack(0))
}