mschwaig

I've been thinking if this could be done in Nix and toyed around with the idea just a little bit using nano-gpt.

Hermeticity always seems to mean isolation, but depending on who you ask it does not always mean computing some sort of hash over all build input as the 'identity' of a particular step in the pipeline, like Nix does.

If you do that hash-based identity part, looking up intermediary results and resuming from there happens using this sort of hash.

Does savanah do that, or will it resume where it left off based on a less strict notion of identity?

I could see arguments for either approach.

A consequence of universal healthcare that people don't talk about much is that it turns unhealthy citizens from an individual cost into more of a collective one. So it makes sense that countries with universal healthcare regulate in favor of their citizens as opposed to their food industry, because they're paying for the consequences more directly.

I think outright shortening copyright terms could be a beneficial policy along similar lines.

I would blame how Austria, a very small country, is organized into 9 provinces that actually have their own budget and can pass their own laws on some topics.

Rail service is funded at the federal level, so there's less arguing about who pays for what. Bus service, however, is managed by regional transport associations funded by the provinces. This creates disincentives for cross-province bus routes because no single province wants to pay more than its 'fair' share for a service that primarily benefits voters in another province.

Similar dynamics play out at the city/province level. Take Linz, the provincial capital of Upper Austria: the city has had a social democratic (SPÖ) mayor continuously since 1945, while the province has had a conservative (ÖVP) governor for exactly the same period of 80 years. This disincentivizes the province government from helping to fund public transport within or into the city, because it's a win for social democratic city voters, while the more conservative rural voters would rather take the car anyway since they often can't do the whole trip by public transport.

Arguably the reason for the excellent public transport in the city of Vienna is that they are also their own province. Their mayor/governor, who has been a social democrat as well for the last 80 years, always controls both levels of funding.

If you make a conventional AI agent do packaging and configuration tasks, it has to do one imperative step after the other. While it can forget, it can't really undo the effects of what it already did.

If you purpose-build these tools to work with Nix, in the big picture view how these functional units of composition can affect each other is much more constrained. At the same time within one unit of composition, you can iterate over a whole imperative multi-step process in one go, because you're always rerunning the whole step in a fresh sandbox.

LLMs and Nix work together really well in that way.

Yes, the cycle times are bad and some ecosystems and tasks are a real pain still.

I also agree with you when it comes to the task of auditing every line of Nix code that factors into a given system. Nix doesn't really make things easier there.

The benefit I'm seeing really comes from composition making it easier to share and direct auditing effort.

All of the tricky code that's hard to audit should be relied on and audited by lots of people, while as a result the actual recipe to put together some specific package or service should be easier to audit.

Additionally, I think looking at diffs that represent changes to the system vs reasoning about the effects of changes made through imperative commands that can affect arbitrary parts of the system has similar efficiency gains.

I mentioned another alternative to adding flake-specific metadata to data structures that are transferred over the network, as part of the signed traces or otherwise, in a comment on that PR Eelco linked.

It's keeping flake-specific data locally, to guarantee that it matches how the user ended up with the data, not how the builder produced it. I think otherwise from the user POV such data could again look misleading.

As a current PhD student (working on Nix stuff) let me take this opportunity to congratulate you on your successful PhD defense and publicly thank you for your writing. That you write and what you write are inspiring.

I work with Nix a lot, and I had never seen `__findFile`.

It's kind of crazy how much there is to know about Nix. I wish there was a bit less surface area to the language. On the other hand it's really interesting how much specialized knowledge there is in the community around various topics. Some people package things, some people write library code, some write glue code that wraps other build tools, some write VM-based tests, some write generators that transform store paths into things like container images, some just manage their dot files, some are experts for how we deal with some specific proprietary ecosystem like cuda, some write infra code or tools around the Nix code, some work on one of the Nix implementations.

Thanks, and thank you for reading! :)

That's great. Feel free to reach out if you want to, I'm happy to answer any questions. It's basically my job, that I really love. :)