//
// simple demo of using recursive functions to operate on arrays
//
def fillArray(a : Array[Int], startIndex : Int) {
  if (startIndex < a.size) {
    a(startIndex) = readInt
    fillArray(a, startIndex + 1)
  }
}
def printArray(a : Array[Int], startIndex : Int) {
  if (startIndex < a.size) {
    println(a(startIndex))
    printArray(a, startIndex + 1)
  }
}
def arrayCombine(a : Array[Int], startIndex : Int,
  combine : (Int, Int) => Int, identity : Int) : Int = 
{
  if (startIndex < a.size) {
    combine(a(startIndex), arrayCombine(a, startIndex + 1, combine, identity))
  }
  else {
    identity
  }
}

def add(x : Int, y : Int) : Int = { x + y }
def multiply(x : Int, y : Int) : Int = { x * y }

val a1 = new Array[Int](6)
println("enter " + a1.size + " values for array:")
fillArray(a1, 0)

println("you entered:")
printArray(a1, 0)

println("sum = " + arrayCombine(a1, 0, add, 0))
println("product = " + arrayCombine(a1, 0, multiply, 1))