> I disagree, the tools (or, well, Ansible, which is the only one I'm familiar with) are declarative, as he describes. He says "these tools are not enough", then goes on to say that you need stateless package management, through a non-sequitur.
There is a fundamental difference between Ansible and co. and NixOS. These tools take you from an unknown state, look at the part of this state you configured in the Ansible files, and apply the modifications necessary. NixOS will take its cue from a single file (possibly with includes) describing the entire machine.
Concretely, if you tell Ansible "package X should be present", apply the configuration and then remove this line before reapplying the configuration, package X will still be present, even though it's not listed in the configuration. I don't mean that as a criticism of Ansible, for my purpose it's about as good as it gets, but it's two different paradigms.
There is a fundamental difference between Ansible and co. and NixOS. These tools take you from an unknown state, look at the part of this state you configured in the Ansible files, and apply the modifications necessary. NixOS will take its cue from a single file (possibly with includes) describing the entire machine.
Concretely, if you tell Ansible "package X should be present", apply the configuration and then remove this line before reapplying the configuration, package X will still be present, even though it's not listed in the configuration. I don't mean that as a criticism of Ansible, for my purpose it's about as good as it gets, but it's two different paradigms.