Curry and functions flexibilities

MapReduce.scala

/**
 *
 * @author Lim, Teck Hooi
 *
 * <br/><br/>30/01/2013 10:19 AM
 *
 */

object MapReduce {
  def mapReduce(f : Int => Int, combine : (Int, Int) => Int, zero : Int)(a:Int, b: Int) : Int =
    if (a > b) zero
    else combine(f(a), mapReduce(f, combine, zero)(a + 1, b))

  def product(f:Int => Int)(a : Int, b : Int) : Int =
    mapReduce(f, (x, y) => x * y, 1)(a, b)

  product(x => x * x)(3, 4)

  def fact(n : Int) = product((n => n))(1, n)

  fact(5)
}