ANSI Identicons in Elixir

identicon.exs

defmodule Identicon do

  def make(username) do
    username
    |> encode
    |> draw
  end

  defp encode(username) do
    :crypto.md5(username)
    |> select_colour
    |> select_alpha
  end

  defp select_colour(md5), do: _select_colour(md5 |> :binary.bin_to_list)
  defp _select_colour([ r, g, b | tail ]), do: { { r, g, b }, tail ++ tail }
  
  defp select_alpha({ { r,g,b }, [a|tail] }), do: { { r, g, b, a }, tail }

  defp draw({_, []}), do: nil
  defp draw({_, [a, b, c, d, e | tail]}) do
    expand([a, b, c, d, e])
    |> map_colours
    |> render

    draw({nil, tail})
  end

  defp expand(array), do: Enum.flat_map(array, &([&1, &1, &1, &1, &1]))

  defp map_colours(array), do: Enum.map(array, &(choose_colour(&1)))

  defp choose_colour(colour) when colour < 86, do: :red_background
  defp choose_colour(colour) when colour < 172, do: :green_background
  defp choose_colour(_), do: :blue_background

  defp render(array) do
    Enum.flat_map(array, &([&1, " "]))
    |> IO.ANSI.format(true)
    |> draw_three
  end

  defp draw_three(string) do
    IO.puts(string)
    IO.puts(string)
    IO.puts(string)
  end

end