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Trying to convince people usually makes any resistance worse.

Using it, solving problems with it, and building a real community around it tend to make a much greater impact in the long run.

Yeah, but if the problem you are solving is rare for most practitioners, effectively theoretical until it actually happens, then people won't switch until they get bit by that particular problem.
But they’re roughly the same paradigm as docker, right? My understanding of the Nix approach is that it’s still reproducing most of a user land/filesystem in a captive/separate/sandbox environment. Like, docker is using namespaces for more stuff, Nix has a heavier emphasis on reproducibility/determinism, but … they’re both still throwing in the towel on deploying directly on the underlying OS’s userland (unless you go all the way to nixOS) and shipping what amounts to a filesystem in a box, no?
I daily drive NixOS. I don't have a global "userland". Packages are shipped from upstream and pull in the dependencies they need to function.

That means unlike Gentoo, I've never dealt with a "slot conflict" where two packages want conflicting dependencies. And unlike Ubuntu, I have new versions of everything.

Pick 2: share dependencies, be on the bleeding edge, or waste your time resolving conflicts.

Yeah nix is great for this. Also I can update infrequently and still package anything I want bleeding edge without any big issues other then maybe some build from sourcing.
> But they’re roughly the same paradigm as docker, right?

Absolutely not. Nix and Guix are package managers that (very simplified) model the build process of software as pure functions mapping dependencies and source code as inputs to a resulting build as their output. Docker is something entirely different.

> they’re both still throwing in the towel on deploying directly on the underlying OS’s userland

The existence of an underlying OS userland _is_ the disaster. You can't build a robust package management system on a shaky foundation, if nix or guix were to use anything from the host OS their packaging model would fundamentally break.

> unless you go all the way to nixOS

NixOS does not have a "traditional/standard/global" OS userland on which anything could be deployed (excluding /bin/sh for simplicity). A package installed with nix on NixOS is identical to the same package being installed on a non-NixOS system (modulo system architecture).

> shipping what amounts to a filesystem in a box

No. Docker ships a "filesystem in a box", i.e. an opaque blob, an image. Nix and Guix ship the package definitions from which they derive what they need to have populated in their respective stores, and either build those required packages or download pre-built ones from somewhere else, depending on configuration and availability.

With docker two independent images share nothing, except maybe some base layer, if they happen to use the same one. With nix or Guix, packages automatically share their dependencies iff it is the same dependency. The thing is: if one package depends on lib foo compiled with -O2 and the other one depends on lib foo compiled with -O3, then those are two different dependencies. This nuance is something that only the nix model started to capture at all.

> Docker ships a "filesystem in a box", i.e. an opaque blob, an image. Nix and Guix ship the package definitions from which they derive what they need to have populated in their respective stores, and either build those required packages or download pre-built ones from somewhere else, depending on configuration and availability.

The rest of your endorsement of NixOS is well taken, but this is a silly distinction to draw. Dockerfiles and nix package definitions are extremely similar. The fact that docker images are distributed with a heavier emphasis on opaque binary build step caching, and nix expressions have a heavier emphasis on code-level determinism/purity is accidental. The output of both is some form of a copy of a Linux user space “in a box” (via squashfs and namespaces for Docker, and via path hacks and symlinks for Nix). Zoom out even a little and they look extremely alike.

> This nuance is something that only the nix model started to capture at all.

Unpopular opinion, loosely held: the whole attempt to share any dependencies at all is the source of evil.

If you imagine the absolute worst case scenario that every program shipped all of its dependencies and nothing was shared then the end result would be… a few gigabytes of duplicated data? Which could plausible be deduped at the filesystem level rather than build or deployment layer?

Feels like a big waste of time. Maybe it mattered in the 70s. But that was a long, long time ago.

I think the storage optimization aspect is secondary, it is more about keeping control over your distribution. You need processes to replace all occurrences of xz with an uncompromised version when necessary. When all packages in the distribution link against one and the same that's easy.

Nix and guix sort of move this into the source layer. Within their respective distributions you would update the package definition of xz and all packages depending on it would be rebuild to use the new version.

Using shared dependencies is a mostly irrelevant detail that falls out of this in the end. Nix can dedupe at the filesystem layer too, e.g. to reduce duplication between different versions of the same packages.

You can of course ship all dependencies for all packages separately, but you have to have a solution for security updates.

Node.js basically tried this — every package gets its own copy of every dependency in node_modules. Worked great until you had 400MB of duplicated lodash copies and the memes started.

pnpm fixed it exactly the way you describe though: content-addressable store with hardlinks. Every package version exists once on disk, projects just link to it. So the "dedup at filesystem level" approach does work, it just took the ecosystem a decade of pain to get there.

nix has a cache too but only if the packages are reproducible.

Much harder to get reproducibility with C++ than JavaScript to say the least.

> If you imagine the absolute worst case scenario that every program shipped all of its dependencies and nothing was shared then the end result would be… a few gigabytes of duplicated data?

Honestly, I've seen projects that do this. In fact, a lot of projects that do this, at the compilation level.

It feels like a lot of the projects that I would want to use from git pull in their own dependencies via submodules when I compile them, even when I already have the development libraries needed to compile it. It's honestly kind of frustrating.

I mean, I get it - it makes it easier to compile for people who don't actually do things like that regularly. And yeah, I can see why that's a good thing. But at the very least, please give me an option to opt out and to use my own installed libraries.

Maybe the RAM crunch will get people optimizing for dedup again.