Scala By Example Chapter 5 Solutions - Exercise 5.2.3

Exercise 5.2.3 Write factorial in terms of product.

	object Factorial {
	def product(f: Int => Int)(a: Int, b:Int): Int = {
	if (a > b) 1 else f(a) * product(f)(a + 1, b)
	}
	def factorial(n: Int): Int = {
	product(x => x)(1, n)
	}
	def main(args: Array[String]) {
	println("Factorial of 6 is: " + factorial(6))
	}
	}

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