If I may rush to the commenter's rescue: Darch addresses your issues with NixOS by combining a familiar set of tools (Arch Linux) with stateless architecture. Its a fantastic welding of extreme package availability and best-in-class documentation with declarative dependability.
It's not clear to me that this really solves the same problems that Nix does.
I'd imagine this solution inherits any problems that pacman has. The Arch wiki states that "if two packages depend on the same library, upgrading only one package might also upgrade the library (as a dependency), which might then break the other package which depends on an older version of the library." (https://wiki.archlinux.org/index.php/System_maintenance) This is one of the problems Nix does not have by design; in fact Nix lets you mix and match packages painlessly.
This also doesn't seem to allow unprivileged users to install packages, which is kind of a side benefit of using Nix.
Docker-esque solutions' issues with reproducibility are well known; I look at https://godarch.com/concepts/images/, particularly how packages are installed:
#!/usr/bin/env bash
pacman -S steam --noconfirm
and I see the same issues that https://blog.wearewizards.io/why-docker-is-not-the-answer-to... warns of. Heck the author even admits this is the case in an adjacent comment: "I want a machine that can be declared and rebuilt deterministically (at least semi-deterministically, rolling distro and all)" (emphasis mine).
Also, frankly, I don't want to run my personal computer like a server, with complete immutability and the need to build fat image files every time I want to try out an additional program. That seems to me like a workflow that's better suited for servers where spending a few minutes for a deploy isn't a blocking operation, and where stateless service design is considered best practice.
> if two packages depend on the same library, upgrading only one package might also upgrade the library
Yes, you are inheriting the nuances of whatever package manager you choose. Maybe another distro can give you a truly fixed package versions? You can also use apt to pin versions. This isn't something that Darch introduced, but also, it isn't something it solves. So yes, if you need 100% deterministic, Nix is your guy. I don't think this is a big issue though on Ubuntu systems, or most non-rolling distros. Their apt updates are typically well tested and don't bump major versions.
> need to build fat image files every time I want to try out an additional program
You can install your packages and use them when you like, without requiring a rebuild. Hell, that is even part of my workflow for some applications like docker. I have dotfiles with a "install-docker" and "install-vmware" aliases that installs it whenever I need it, instead of baking it into images.
> That seems to me like a workflow that's better suited for servers where spending a few minutes for a deploy isn't a blocking operation, and where stateless service design is considered best practice.
I disagree. If this was the case, then why Nix then? Obviously, stateless is valuable. I have multiple machines that I perform common tasks on. I hate having to always manage the updates when I get back to each one of them. With Darch, I can deploy one single image to all devices, and be confident they will never drift in installed packages/configuration. I never again have to ask my self "what machine am I on again?". Stateless may be the definitive way to run servers, but that by no means restricts it to only servers. I have been running Darch for a few months now, and I find it incredibly useful and calming.
> So yes, if you need 100% deterministic, Nix is your guy.
There are two orthogonal problems here: a lack of package isolation and nondeterminism.
Nix isolates packages, such that updating one package has no impact on any other packages (with unavoidable exceptions like the graphics driver, presumably).
You're right that package isolation isn't much of a problem on non-rolling distros. One of the benefits of Nix is that you get some of the stability and predictability of an LTS distro with the freshness of a rolling distro when desired, without having to deal with package conflicts.
Incidentally, Nix doesn't need to be used in a deterministic manner. In fact, I don't think most desktop users of Nix care too much about determinism for most packages they run. I certainly don't; I'm happy to follow along with whatever arrives in my channel. Nix has features that support determinism, and I'm certainly glad they exist for when I end up needing them, but they're not necessarily why people use Nix.
> Obviously, stateless is valuable.
When I said "stateless", I was referring to the whole "cattle, not pets" view of servers, where the running state of any particular server is unimportant, with nothing in the filesystem being of value. I was arguing that needing to build a new image and reboot in order to change which packages are installed are a poor fit for the desktop use case, where frequent reboots are much more inconvenient than for the server use case.
I'm not sure what taohansen meant when they used the word "stateless"; they seem to mean something different when they say that.
Anyways, this point is not really applicable anymore, since you've stated:
> You can install your packages and use them when you like, without requiring a rebuild.
Presumably if you install additional packages uncontrolled by your tooling, then your systems can start to drift away from each other.
Nix does not have this compromise; there's no build step. At any given point in time you can reproduce whatever configuration you have on one machine on another machine, regardless of how piecemeal you arrived at that configuration.
