//
// simple demo of using recursive functions to operate on lists
//
def fillList() : List[Int] = {
  val input = readLine
  if (input == "quit")
    Nil
  else
    input.toInt::fillList()
}
def printList(list : List[Int]) {
  if (list != Nil) {
    println(list.head);
    printList(list.tail);
  }
}
def listCombine(list : List[Int], 
  combine : (Int, Int) => Int, identity : Int) : Int = 
{
  if (list != Nil) {
    combine(list.head, listCombine(list.tail, combine, identity))
  }
  else {
    identity
  }
}
println("enter values for list, quit to end:")
val list1 = fillList()

printList(list1);

println("sum = " + listCombine(list1, (x,y)=>(x+y), 0))
println("product = " + listCombine(list1, (x,y)=>(x*y), 1))
println("min = " + listCombine(list1, (x,y) => (x min y), Int.MaxValue))
println("max = " + listCombine(list1, (x,y) => (x max y), Int.MinValue))