make pre-commit persisting errors about agda-unimath

[VojtechStep]

I think that might be a Python version issue - the list[int] generic syntax, which the error complains about, should be available since Python 3.9; which version are you using?

[emilyriehl]

I'm using ubuntu in case this is relevant.

When I type

python --version

it tells me the command is not found. When I type

python3 --version

it returns Python 3.8.10. I've just now managed to install python3.9 so

python3.9 --version

returns Python 3.9.16 (but the python3 version is unchanged).

I believe I may be using a package called "python-is-python3". I forget exactly why. The make pre-commit error message looks the same as before.

[VojtechStep]

I personally don't have experience with how Ubuntu handles Python updates, so take the following with a grain of salt.

If running python says that the command is not found, then that's perfectly fine - a Python script should specify whether it's using python3 or python2, and having the python command as a shorthand for one of them is more of a user-facing convenience. That's actually what the python-is-python3 package does - it creates a link so that running just python is the same as running python3 (and since python isn't found on your system, you don't have python-is-python3 installed).

Since you installed the python3.9 package, you now have two python installations on your system - the default Python 3.8 (accessible via python3), and the new Python 3.9 (accessible via python3.9). If you want to make Python 3.9 the default (thus a script beginning with #!/usr/bin/env python3, such as our pre-commit hooks, would run that instead of 3.8), then you can use Ubuntu's update-alternatives tool.

However, as I'm reading more into this, it seems that people usually caution against messing with the default python3 version, since pretty much all system components have a dependency on it, and who knows what changing the version would break.

I think the better solution would be for our pre-commit hooks to support Python 3.8, since that's the default for Ubuntu 20.04 LTS, which will be supported until mid-2024 (with "Extended Security Maintanance" period reaching into 2030). I'll look into it.

[emilyriehl]

Thanks! I'll wait for further instructions.

[VojtechStep]

Ok, so it seems like pre-commit actually uses its own python, not the system-wide version, which is good. But unfortunately I can't reproduce your issue, my hooks run just fine.

On my system, there's this directory ~/.cache/pre-commit/repoabbobbu8/py_env-python3.10/. Could you check if you have something similar? I'm not sure if the repoabbobbu8 part is deterministic, and there might be multiple such folders under ~/.cache/pre-commit, but could you look around and find one with a py_env-python-3.X subdirectory?

[VojtechStep]

Well, the Python version selection story is a little more disappointing than I thought, so I went and changed the offending piece of code to be compatible with Python 3.8; this PR should fix the issue: #634.