PEP 586: Literal Types

[Michael0x2a]

This is a pull request for a new PEP proposal for adding a new category of types to the PEP 484 typing ecosystem -- Literal types.

Some procedural things:

1. Although this PEP was not discussed in python-ideas, it has been discussed in the typing-sig mailing list and in my draft pull request over the past few months. I'm submitting this PEP now so it can start going through the standard acceptance process (whenever it starts).
2. We've implemented the bulk of this PEP in mypy. The only things currently missing is support for Enum Literals and some of the more complex inference suggestions in this PEP. We plan on adding in those missing gaps over the next month or so.
3. One of the co-authors (Ivan Levkivskyi) is a core Python developer. I understand that means it's ok to leave out the "Sponsor" field?

[Michael0x2a]

@gvanrossum -- I took 586, as you suggested.

[gvanrossum]

Hi Michael, as a PEP editor I've merged your PR. This just means that the PEP conforms to the procedural and formatting requirements. If you have updates, just send another PR and one of the PEP editors will merge them. (PEP editors don't judge a PEP by its contents, only by its form.)

The process to acceptance is then roughly as follows:

1. Start a debate on typing-sig.
2. Once there's rough consensus, send a formal request for approval. I believe that should just go to python-dev. (We're not actually very formal about this. :-)
3. The Steering Council will then assign a BDFL-Delegate. (I'll probably volunteer.)
4. The BDFL-Delegate will guide you through the remaining process. (If the typing-sig debate ends with clear consensus there's not much more to do at this point.)

Good luck!