Roman numerals kata in Elixir lang. My very first use of the language >_<

gistfile1.ex

Code.require_file "../test_helper.exs", __FILE__

defmodule ElixirRoman1Test do
  @moduledoc "Tests number to roman numerals"
  use ExUnit.Case

 
  defp romans_list do
    HashDict.new [ {10, "X"}, {9, "IX"}, {5, "V"},
                   {4, "IV"}, {1, "I"}]
  end

  def roman(0) do
    ""
  end

  @doc "Returns the roman number representation of nr"
  def roman(nr) do
    {num, rom} = get_biggest_roman_less_than(nr)
    rom <> roman(nr - num)
  end

  defp get_biggest_roman_less_than(nr) do
    [{num, rom} | _ ] = Enum.reverse Enum.filter romans_list,
      fn({key, value}) -> nr >= key end
    {num, rom}
  end
  
  test "roman 0 should return empty string" do
    assert "" == roman(0)
  end

  test "roman 1 should return I" do
    assert "I" == roman(1)
  end

  test "roman 2 should return II" do
    assert "II" == roman(2)
  end

  test "roman 5 should return V" do
    assert "V" == roman(5)
  end

  test "roman 34 should return XXXIV" do
    assert "XXXIV" == roman(34)
  end
end