I know that a lot of what Nix does is working around its break from FHS, but I can imagine there are still things that seep through. Are there any unsolvable problems due to this?
I saw on this post that it is possible to use FHS on Nix. Does this solve all potential issues then?
Why isn’t this done on the actual system and by default? That would make it fhs compliant, no?
If you put an FHS on the actual system you wouldn’t be able to install multiple versions of the same package, updates wouldn’t be atomic - you wouldn’t get the big selling points of Nix.
If your system uses 3 different Pythons as dependencies of different packages, which one gets to be /usr/bin/python?
The most recent one by default unless another is manually chosen. The nix packages can keep using their specific versions directly
Now you’ll have a zillion users trying to install software in ways that violate all the assumptions that NixOS operates on, but which are still tightly coupled to your NixOS config. Now updates to your system, or even seemingly unrelated config changes (through some transitive dependency chain) can easily break that software.
So now we’ve basically removed half the advantages that motivate Nix/OS in the first place, and when stuff breaks it will look like it’s Nix’s fault, even if it isn’t.
On the other hand, nixpkgs is already the most comprehensive repository of system software out there, and for 99% of packages Nixifying it is pretty trivial. Hell, my NixOS config does that for 3 different GitHub repos right inline in my config.nix