Check if two lists have the same members in any order. Considers duplicated values.

are_eq.ex

def are_eq?(left, right) when is_list(left) and is_list(right), do: same_members?(left, right)

defp same_members?([hd_left | t_left], [_ | _] = right) do
  if Enum.any?(right, &(&1 == hd_left)) do
    index = Enum.find_index(right, &(&1 == hd_left))
    {_, next_right} = List.pop_at(right, index)

    same_members?(t_left, next_right)
  else
    false
  end
end

defp same_members?([], []), do: true
defp same_members?([], [_ | _]), do: false
defp same_members?([_ | _], []), do: false