GuixSD? Only because Guix was build from Nix. Frankly I don't think there's anything else like it. I don't know Arch enough to compare, but there's something a

GuixSD? Only because Guix was build from Nix. Frankly I don't think there's anything else like it. I don't know Arch enough to compare, but there's something also similar to Gentoo, except Nix knows that if source + dependencies + architecture + configuration is the same it will pull compiled version from cache, if something changes it will recompile it. The killer NixOS feature is that it has a single configuration file that's declarative which you can use to describe your OS, so it has something like salt/ansible/chef/puppet built in, and unlike them it's also is truly declarative. For example if you have package installed, to remove it, you just remove it from the list, where in those tools you need to create a state that ensures the package must not be present. Edit: from other comments I see that you meant that packages in arch are not modified, I guess Nix does follow that and only add patches if it absolutely needs them to make application work correctly, but unlike other distros nix also allows user trivially (ignoring the steep curve to learn nix :) to modify a derivation (for example applying patches, changing dependencies, changing ./configure flags) similarly how you would extend a class in OO language. In any other OS to do such customization, you would need to generate a new package, place it in package repo, and worry about your modified package breaking other parts of the system. NixOS will then recompile that package and use it (if you use caching it will pull from cache)