Lazy path iterator in Elixir

recursive_path_iterator.ex

defmodule RecursivePathIterator do
  @moduledoc """
  This module provides a simple interface for iterating over filesystem directories.
  """

  @doc """
  Walks the given `path` recursively.
  """
  @spec walk(Path.t) :: Enumerable.t
  def walk(path) do
    case File.ls(path) do
      {:ok, files} ->
        files
        |> Stream.map(&Path.join(path, &1))
        |> Stream.map(&iterate/1)
        |> Stream.concat()
      {:error, _reason} ->
        []
    end
  end

  #
  # Helpers
  #

  defp iterate(path) do
    if File.dir?(path),
      do: walk(path),
    else: [path]
  end
end