pin.ex

defmodule Pin do

  def generate(length \\ 4) when is_integer(length) and length >= 0  do
    Enum.join(gen_pin(length))
  end

  defp gen_pin(1) do
    [:rand.uniform(9)]
  end

  defp gen_pin(length) do
    gen_pin(length - 1) ++ [:rand.uniform(9)]
  end

end