Heuristic to infer whether a list should be printed as charlist in IEx - An improvement proposal

improved_heuristic_inference.exs

defmodule HeuristicInference do
  @moduledoc """
    Heuristic to infer whether a list should be printed as charlist in IEx.
    An improvement proposal.
  """

  def should_print_as_charlist?([]) do
    true
  end

  def should_print_as_charlist?([head | tail]) do
    should_print_head_as_charlist =
      cond do
        is_integer(head) -> List.ascii_printable?([head])
        is_list(head) -> should_print_as_charlist?(head)
        true -> false
      end

    should_print_head_as_charlist and should_print_as_charlist?(tail)
  end
end

ExUnit.start()

defmodule HeuristicInferenceTest do
  use ExUnit.Case

  @input_to_expected_output %{
    [] => true,
    [0] => false,
    [?a] => true,
    [0, ?a] => false,
    [?a, ?b] => true,
    [[?a, ?b], [0, 1]] => false,
    [[?a, ?b], [?c, ?d]] => true,
    [[[?a], [?b]], [[?c], [?d]]] => true,
    [[[?a], [0]], [[?c], [1]]] => false,
    ["oops"] => false,
    [true] => false,
    [%{"one" => :two, 3 => "four"}, [2], [72]] => false
  }
  test "input and expected output pairs (literals)" do
    @input_to_expected_output
    |> Enum.each(fn {input, expected_output} ->
      assert HeuristicInference.should_print_as_charlist?(input) == expected_output
    end)
  end
end