Código para adivinha um número passado dentro de Range

binary_search.exs

defmodule BinarySearch do
  def guess(number, a..b), do: guess(number, a..b, calc_half(a, b))

  def guess(number, _, number) do
    IO.puts("Is it #{number}")
    IO.puts(number)
  end

  def guess(number, _..b, my_guess) when number > my_guess do
    IO.puts("Is it #{my_guess}")
    guess(number, my_guess..b, calc_half(my_guess, b))
  end

  def guess(number, a.._, my_guess) when number < my_guess do
    IO.puts("Is it #{my_guess}")
    guess(number, a..my_guess, calc_half(a, my_guess))
  end

  defp calc_half(a, b), do: div((b-a),2) + a
end