`getn` implemented using raw mode in OTP 28

getn.exs

defmodule Getn do
  def getn(prompt, count \\ 1) do
    if System.otp_release() >= "28" do
      case :shell.start_interactive({:noshell, :raw}) do
        :ok -> getn_raw(prompt, count)
        _error -> gets_cooked(prompt)
      end
    else
      gets_cooked(prompt)
    end
  end

  defp getn_raw(prompt, count) do
    IO.write(prompt)
    resp = get_chars(count)
    IO.write("\r\n")
    :shell.start_interactive({:noshell, :cooked})
    resp
  end

  defp get_chars(count) do
    if count <= 0 do
      ""
    else
      resp = IO.getn("", count)
      IO.write(resp)
      resp <> get_chars(count - String.length(resp))
    end
  end

  defp gets_cooked(prompt) do
    prompt
    |> IO.gets()
    |> String.trim_trailing("\n")
  end
end

resp = Getn.getn("1 char: ", 1)
IO.puts("got: #{inspect(resp)}")

resp = Getn.getn("2 chars: ", 2)
IO.puts("got: #{inspect(resp)}")