So this isn’t great: $ nix-env -i python3 installing 'python3-3.10.0a5' Why isn’t this great? Well, because in the Python versioning scheme, python3-3.10.0a5 is short for “Python 3.10.0 alpha version 5.” The latest stable release of the Python reference implementation, right now, is actually 3.9.5. 3.10 is currently considered the “pre” branch, and 3.11 is currently the “dev” branch. I think; I’m not really a Python person. So it’s not great that a new Nix user might try to install python3 and wind up with some random alpha version of Python (the latest in the 3.10 branch is actually 3.10.0b2, for whatever that’s worth). But it’s even less great because – at the time that I am writing these words right now – the python3-3.10.0a5 derivation is broken, and will not build.