Scala 2.8 generic Numeric type

factorial.scala

// Generic factorial function
// require Scala 2.8
def factorial[T](n: T)(implicit m: Numeric[T]): T = {
  import m._
  if (n == zero) one else n * factorial(n-one)
  // this is not tail-optimized
  // StackOverFlow for n > 26,800 BigInt on my JVM (1.6 OS X)
}

factorial_tail.scala

// Generic factorial function (tail optimized)
// require Scala 2.8
def factorial_tail[T](n: T)(implicit m: Numeric[T]): T = {
  import m._
  def loop(n: T, acc: T): T = if (n <= zero) acc else loop (n - one, acc * n)
  loop(n, one)
}