Python 2 is still the only python provided out of the box on Mac.

Python 2 is EOL in just over a year. Why would anyone write for a piece of software that will be completely unsupported in 18 months?

Because, it is installed on Macs, as I said. I don't want to have to teach people how to install python 3, when they already have python 2, which is fine.

Also, redhat had promised support for a while yet, and I expect spoke to keep it working until they replace with Python 3 (or remove python altogether?)

> Because, it is installed on Macs, as I said.

Apple also only supports very ancient set of GNU tools. That doesn't mean that in the majority of cases it is a wise choice to lock yourself to those same outdated tools - especially on a platform that hasn't guaranteed the presence of said tools.

> I don't want to have to teach people how to install python 3, when they already have python 2, which is fine.

I haven't directly addressed anything to do with your personal choices. However, this thread started with the quote:

> no python 2 support means no python support

Which frankly, isn't true. Python 2 is about to be EOL'd.

> Also, redhat had promised support for a while yet

I wouldn't depend upon it being long-term however. RHEL8 drops Python 2, and RHEL 7.5 deprecated it. [0]

[0] https://www.phoronix.com/scan.php?page=news_item&px=RHEL-8-N...

Who are you teaching to use Python and a bleeding-edge library like the OP's? You're not teaching them how to install Python virtualenvs, or how to install homebrew?

Yes, but the fact that running `swift` in command line while system python is active spews an unholy amount of error messages is an indication than even there it is going away.