Comment by otikik
11 hours ago
I see this:
> The consequence is me, spending a few hours debugging my environment instead of writing code.
But then I also see this:
> I’ve spent a lot of time recently moving my entire workflow into a declarative system using nix.
I can see how this can be beneficial for someone who switches systems very often, reinstalls their OS from scratch very often, or just derives a lot of pleasure/peace of mind knowing that their dev env is immutable.
I change computers once every 6 years or so, maybe more. To me this looks like exchanging a couple (hypothetical) hours of debugging 6 years in the future by tens of (guaranteed) hours trying to climb up the nix learning cliff.
I am happy that it works for the author though, and knowing that it's possible is good in case my particular development circumstances change.
Long-time (by now) Nix user here. It's even worse than a few hours of debugging. In my experience it requires continuous maintenance, options tend to be deprecated and moved around on a regular basis (at least in NixOS and home-manager), things like NeoVim break regularly as a result of friction between the immutable world and a lot of plugins expecting a mutable world, etc. I do install my Mac from scratch every 6 months or so (I like a clean system), but with a dotfiles repo and Homebrew, it takes me about an hour to set everything up again, which is far less time than maintaining a Nix-managed system.
For me Nix/NixOS is by far the most effective for deploying servers, development VMs, etc. I do this regularly, so it pays off - I have a familiar environment completely set up in minutes. Another place it pays off, even on macOS, is for development environments, especially if you have to pull in a lot of native dependencies (which can happen in mixed Python + C++ projects, mixed Rust + C/C++ projects, etc.).
Nix shines in all difficult cases, like setting up complex cross-compilation environments, building for old glibc versions, etc. You set it up once and then it's really easy for yourself and other project contributors to get the same build environment.
Like any tool, a good engineer knows when to apply it.
It sounds like you're on unstable? Things are significantly more stable if you stick to the release branches (25.05, 25.11 etc)
Nix is not worth it if all you want is configuring your home computer. The learning curve is steep and has a tall onboarding cliff.
The only way you get positive ROI from Nix is either you enjoy the journey, or you use it to do more than just managing a single computer: you manage a fleet, you build thin application container images, you bundle all your software, you have devshells, repeatable tests and deploys, etc. It's the same tool for all of them.
It's worth it for me. I learnt and set up my home manager config once in 2024 and I now only occasionally make light tweaks. But I deploy it on every personal computer or remote development servers at my jobs (previous and current). Granted, I'm probably one of the handful of people in my community who uses nix, because it's too arcane - but I've already paid the cost.
Right.
Nix is a wonderful technology. But I would not argue it is practical if you can afford "just fix it when it breaks". A nix setup more/less requires you to pay all the cost up front.
I appreciate putting in the effort now so that I don't have to later for stuff like declarative dev environments. It's really nice to not have to copy-and-paste installation instructions from a README. -- I did like the point: until you've felt what a comfortable design is, you cannot imagine it.
Yeah, I'm a Nix user and fan but I'm still going to be stuck fixing it when it breaks. The biggest thing that I have to remind myself is that reproducible != "just works." Once you get to what you want, you're set but until then and every change after, there's a chance you'll be in the weeds.
At least from my usage, the fact that your configuration is all tied to whether the entirety of nixpkgs-unstable is working can be a real headache. Like recently when CMake was upgraded to 4.0, it took down a healthy handful of packages, which meant you couldn't update anything until things were resolved or you were really fluent in Nix hackery. (I was the former)
In the six years you are using your computer, do you ever expect to run into versioning issues and conflicts? Homebrew packages conflicting with local packages, something you compile give needs a different python/ruby/node/rust/whatever version that you have locally installed, you want to quickly try out a new package or upgrade without changing your system but have the option of rolling back safely, need to quickly install a database, want to try out a new shell and shell config but don't brick your system and have the option to roll back, etc. Nix gives you all of that and more for a one-time setup cost. Your argument is correct only if you expect to never change anything on your computer for the 6 years. But if I think about how often I have fought with homebrew or some kind of versioning/path/binary conflicts in the past then the investment in nix has paid off exponentially.
It's also about peace of mind like you said. Before nix I sometimes felt anxiety installing or upgrading certain things on my computer. "Will this upgrade break stuff?" - and often it did and I'd have to spend the next few hours debugging. With nix I don't worry about any of that anymore.
That's mostly solved with env managers for python/ruby/node/..., takes at most a few minutes to fully set up and learn, and doesn't get constantly broken by macOS updates.
Even for things like trying out a new shell you can temporarily move the dotfiles somewhere and restore them back and it still takes less time than converting everything to Nix.
But now you’re stuck with Python. Nix enables trivially simple dev environments that are completely heterogenous. This gives you a powerful form of freedom because it literally opens up the entire software universe to your dev environment in a confidence inspiring way. Not to mention things like parameterising anything you use reliably and setting up environment variables, shell scripts, database service whatever you want. Also integrates with tools such as UV really well. Yes, the language is terse and difficult but once you know it, it’s liberating, and makes you a better software developer in my opinion because you now have a high-end full workshop rather than a small toolbox.
This is my feeling too. Nix is a relatively high time investment for a tool that tries to do everything, when you might not need or want everything and using the specific language’s tooling is more than sufficient and quicker. It takes a few minutes to install and do `uv sync`, or `nvm install`, or whatever, on a repository on a new computer, and it just works. Until Nix gets there, and I’m skeptical it will because of the “purist” mindset a lot of people in the community have, it’s hard to justify it.
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Fully spot on, I don't get what is that hard to set a couple of environment variables, and mayby symbolic links, depending on the OS and language being used.
A simple UNIX script or PowerShell utility takes care of it.
None of the ones I have used during the last decades has ever grown to more than like 20 lines of code, minus comments.
> Even for things like trying out a new shell you can temporarily move the dotfiles somewhere and restore them back...
I think the closest mainstream UX for "you can try out this program without having to install it" is running a Docker image.
:) I'd say Nix is second best at everything related to packages.
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> I change computers once every 6 years or so, maybe more. To me this looks like exchanging a couple (hypothetical) hours of debugging 6 years in the future by tens of (guaranteed) hours trying to climb up the nix learning cliff.
yes, it sounds like it's not worth it for you -- you will have to spend a significant amount of time converting your system to do things "the nix way". you can try to do this incrementally, but it's a time sink, and really easy to get stuck bikeshedding instead of doing work.
for me, it feels like a near equal trade-off between debugging nix, or debugging some random env issues that pop up. i know nix, claude code "knows" nix, a lot of other people online know nix. random env issues are random, and yield worse results on google, and frankly are much more frustrating to the point i would rather spend more time with nix than deal with them. maybe a very weird view.
I have experienced a positive return on investment from using Nix Darwin and devenv.sh since getting a new Mac two years ago. Did not spend too much time learning neither.
Also with migration assistant on Mac you basically do not need this in anyway shape or form.