A binary search demo in Elixir(from "Programming Elixir" book, Chapter 6)

binary_search_demo.exs

defmodule Chop do
  def guess(final, range) do
    low..high = range
    middle = div(low + high, 2)
    _guess_helper(final, low, high, middle)
  end

  defp _guess_helper(final, _low, _high, middle) when final === middle do
    middle
  end

  defp _guess_helper(final, low, _high, middle) when final < middle do
    IO.puts "Is it #{middle}"
    _guess_helper(final, low, middle, div(low + middle, 2))
  end

  defp _guess_helper(final, _low, high, middle) when final > middle do
    IO.puts "Is it #{middle}"
    _guess_helper(final, middle, high, div(middle + high, 2))
  end
end