Probably not the best we can come up with!

dice.ex

defmodule Dice do
  @moduledoc """
  The best I could come up with...

    iex> import Dice
    ...> ~d'1d6'+3
  """

  def sigil_d(input, []) do
    [n, eyes] =
      String.split(input, "d", parts: 2)
      |> Enum.map(&String.to_integer/1)
    # Baby needs a new pair of shoes!
    Stream.repeatedly(fn -> :rand.uniform(eyes) end)
    |> Enum.take(n)
    |> Enum.sum()
  end
end