factorial in scala

factorial.sc

// write a program to print factorial of a given integer


def factorial(n: Int): Long = {

  @annotation.tailrec // asks compiler to raise a compile error if unable to do tail call recurssion optimization
  def loop(num: Int, acc: Long): Long =
    if (num > 1) loop(num - 1, acc * (num - 1))
    else acc

  loop(n, n)
}

println(factorial(25))