elixir_binary_search.ex

defmodule BinarySearch do
  def find(item, _left, [i | _right]) when i == item, do: true
  def find(item, _left, [i | right]) when i < item, do: find(item, right)
  def find(item, left, [i | _right]) when i > item, do: find(item, left)
  def find(_item, _left, []), do: false

  def find(item, list) do
    {left, right} = split(list)
    find(item, left, right)
  end

  def split(list) do
    len = round(length(list) / 2)

    case Enum.split(list, len) do
      {left, []} -> {[], left}
      res -> res
    end
  end
end