Basically it solves the problem a different way than you think. Instead of allowing you to control order, it removes the possibility of order mattering at the system level.<p>Nix and Guix use special file structures to make sure everything is isolated so no build can affect another, unless there is a depedency, in which case one will be built before the other.<p>It is this powerful isolated file structure that allows NixOS and GuixSD to deliver on the promise of deterministic system set up in a way Puppet and Chef will never be able to. It works incredibly well.