enum_utils.ex

defmodule PhenixDisplays.EnumUtils do
  @doc """
  Make a sliding window of a list

  ## Example
    iex> alias PhenixDisplays.EnumUtils
    iex> EnumUtils.sliding([1,2,3], 2)
    [[1, 2], [2, 3]]
    iex> EnumUtils.sliding([1,2,3,4], 2)
    [[1, 2], [2, 3], [3, 4]]
    iex> EnumUtils.sliding([1,2,3,4], 3)
    [[1, 2, 3], [2, 3, 4]]
  """
  def sliding(list, n) do
    do_sliding(list, n, [])
  end

  defp do_sliding([], _, acc), do: acc
  defp do_sliding([_ | tl], n, acc) when length(tl) < n - 1, do: acc
  defp do_sliding([hd | tl], n, acc), do: do_sliding(tl, n, acc ++ [[hd] ++ Enum.take(tl, n - 1)])
end