I know that Nix users respect Guix (well, the ones who talk on IRC, at the very least), and I'm sure it's mutual ... and I think it's very helpful to make this mutual respect public!
Use Nix, respect Guix, can confirm
The only reason I'm not using/learnign Guix (or contributing meaningfully to Nixpkgs these days, for that matter) is time
And I use Guix, and respect Nix :)
Can I somehow have NixOS package universe with Guix language?
You cannot use Nix package definitions with Guix. You can, however, easily extend or modify Guix packages. New package definitions can inherit from existing ones and override fields that you may want to change.
There is also an API for rewriting dependencies recursively:
https://www.gnu.org/software/guix/manual/en/html_node/Defini...
You can also use Nix as a package manager on top of a Guix system (and vice versa).
Most Nix packages, yes, but the NixOS packages specifically (the ones that build Linux), probably not. NixOS and Guix have slightly different philosophies, e.g. about nonfree software (Guix is generally opposed to including it, although I'm not an expert on the details, while NixOS disallows it by default but only by default), and this affects e.g. device driver packages.
I'd like to emphasize more on how much Nix and Guix share and that for the better part Guix should be thankful to Nix!
With regard to Mozilla, Rust might precisely _not_ be such a mistake, but you are right, I should praise Mozilla for moving on then (although I know nothing about Rust, so I can only guess here).
> I'm not sure adding a numeric tower and Turing-completeness is really desirable.
That's what I meant: Turing-completeness comes for free, it does not harm the project and you'll need it sooner or later. Even if the devs don't need Turing-completeness, not adding it to a project is effectively limitating what the user can do with a program.
I fell for it myself and at the time, I had the feeling that "a Turing-complete language might be too much for the project." Today, I believe that this thought is mostly an ungrounded gut-feeling.
> Hydra
Thanks for pointing it out, you are right I should have mentioned it when I wrote about the continuous integration. Will do.
Guix itself uses Hydra on the old server and Cuirass (a Scheme-based CI system :p) for the new one.