Guess exercise in Elixir from PragProg's Programming Elixir book

chop.ex

defmodule Chop do
  def guess(actual, range) do
    low..high = range
    
    mid = div(low + high, 2)
    IO.puts("Is it #{mid}")
    
    _guess(actual, low, high, mid)
  end
  
  defp _guess(actual, low, _high, mid) when actual < mid, do: guess(actual, low..mid)
  defp _guess(actual, _low, high, mid) when actual > mid, do: guess(actual, mid..high)
  defp _guess(actual, _low, _high, mid) when actual == mid, do: IO.puts(mid)
end