Hello! During the typing meetup from a week or two ago, I mentioned that we (the mypy team) were planning on implementing Literal types and would have a draft of the proposed semantics ready soon. Well, here it is: https://github.com/Michael0x2a/peps/blob/literal-types/pep-9999.rst It basically combines and elaborates on the discussion from https://github.com/python/typing/issues/478 and https://github.com/python/mypy/issues/3062, so hopefully there shouldn't be too many surprises. This is probably a little premature in that we've only just barely started the PoC work in mypy: we'll almost certainly need to tweak some things as we work through the implementation. But we're reasonably happy with the proposed semantics and thought it would be nice to just publish it now so that people can start giving feedback. (Also, I guess we wanted an excuse to try using this shiny new mailing list, lol) -- Michael