//
// simple demo of using recursive functions to operate on lists
//
println("type in list values (integers), quit to end")
val list = fillList()

println("you entered:")
printList(list)

println("sum is " + sumList(list))
println("product is " + productList(list))

def fillList() : List[Int] = {
  val input = readLine
  if (input == "quit") {
    List[Int]()
  }
  else {
    val num = input.toInt
    num :: fillList()
  }
}

def printList(ll : List[Int]) {
  if (!ll.isEmpty) {
    println(ll.head)
    printList(ll.tail)
  }
}

def sumList(ll : List[Int]) : Int = {
  if (!ll.isEmpty) {
    ll.head + sumList(ll.tail)
  }
  else {
    0
  }
}

def productList(ll : List[Int]) : Int = {
  if (!ll.isEmpty) {
    ll.head * productList(ll.tail)
  }
  else {
    1
  }
}