I am following Martin Odersky coursera examples herein

ScalaExample.sc

package learn.scala

object Exercise {
  println("Welcome to the Exercises")             //> Welcome to the Exercises
  
  // EXERCISE 1:
  // Write a product function that calculate product of values of a function for the points
  // on a given interval
  
  def prod(f: Int=>Int, a: Int, b: Int): Int =  {
  	if(a > b) 1 else{
  		f(a) * prod(f, a+1, b)
  	}
  }                                               //> prod: (f: Int => Int, a: Int, b: Int)Int
  
  prod(x=>x, 1, 5)                                //> res0: Int = 120
  
  // EXERCISE 2:
  // Write Factorial in terms of product
  
  def factorial(a: Int): Int = {
  	prod(x=>x, 1, a)
  }                                               //> factorial: (a: Int)Int
  
  factorial(10)                                   //> res1: Int = 3628800
}