defmodule QuickSort do
  def sort([]), do: []

  def sort([x | xs]) do
    with {:ok, smaller} <- {:ok, Enum.filter(xs, &(&1 <= x))},
         {:ok, larger} <- {:ok, Enum.filter(xs, &(&1 > x))} do
      sort(smaller) ++ [x] ++ sort(larger)
    end
  end
end