> On 3 Nov, 2017, at 4:01 PM, Victor Stinner <victor.stinner@gmail.com> wrote:
>
> The question is if you would only need <Python 3.7> or <Python 3.7 +
> pip install typing>.
>
> If typing is removed from the stdlib, you can still use it in your
> application. It's "just" another dependency no?
The ideal situation is that something is built-in and just works, examples: dicts, lists, sorted().
So, if you have to import it to use it, it's still great but less seamless, current example: regular expressions. Let's say Guido suggests we should import sorted, dict, and list before use. Not a big deal, right? I mean, how many applications do you know that don't use any other imports?
Finally, if you have to find a third-party package, add it to requirements.txt and manage the dependency forward, that's even less seamless. The standard library has a pretty conservative approach to backwards compatibility. On the other hand, third-party libraries often don't. Sure, there's noble exceptions but the general feel is that you need to be more careful with dependencies from PyPI. If somebody suggested that regular expressions or dictionaries should be moved to PyPI, in my book that would suggest strange things will start happening in the future.
So, the difference is in perceived usability. It's psychological.
I think another psychological side-effect of removing 'typing' is how strongly people will view the guidance that annotations are generally expected to be type hints. With 'typing' in the stdlib, it made that assumption a bit strong, especially if the stdlib ever started to use type hints itself. But by saying "we expect annotations will be used for type hints, but we actually don't do that in the stdlib nor provide a mechanism for actually specifying type hints", that weakens the message. It starts to feel like a "do as I say, not as I do" bit of guidance (which to me is different than the worry that the usage of type hints will decrease).
But that might be fine; I personally don't know. But my suspicion is we will see an uptick of alternative annotation uses that aren't type hints if we take 'typing' out, and that's something we should be aware of and okay with.