Here’s a standalone demo:

Mix.install([
  {:dirent, git: "https://github.com/team-telnyx/erlang-dirent.git", branch: "master"}
])

target_path = "."

Stream.resource(
  fn ->
    {:ok, dir_ref} =
      target_path
      |> String.to_charlist()
      |> :dirent.opendir()

    dir_ref
  end,
  fn dir_ref ->
    case :dirent.readdir_type(dir_ref) do
      :finished ->
        {:halt, dir_ref}

      {:error, reason} ->
        {[{:error, reason}], dir_ref}

      {name, type} ->
        {[{List.to_string(name), type}], dir_ref}
    end
  end,
  fn _ -> :ok end # not used because :dirent cleans up on GC
)
|> Stream.each(&IO.inspect/1)
|> Stream.run()

Followup thoughts in no particular order:

• This uses :dirent.readdir_type since the first question that code that consumes the stream is likely to ask is “is this a directory?”

• The error handling is somewhat inconsistent; a failure in opendir will crash but a failure when iterating through the results will put {:error, reason} in the output stream. Your application may have different needs.

• the situation with filenames that can’t be represented in UTF8 is complicated so this code completely ignores it. That may not be sufficient depending on your specific filesystem.