階乗

#!/usr/bin/env elixir
defmodule Foo do
  def fact(n) do
    fact(n, 1)
  end

  defp fact(0, acc) do
    acc
  end

  defp fact(n, acc) do
    fact(n - 1, acc * n)
  end
end

IO.puts Foo.fact(65535)

real   0m13.120s
user    0m12.577s
sys 0m0.201s