alt Hacker News"proving code correct has been a research topic at some point."
It has been an area of active research for 40 years. But almost all the research returned the null result, meaning that the program proving didn't improve code quality (basically it didn't work). Yet somehow a group of programmers, usually fresh out of academia falls for program proving each generation. Strong types do really help but you need a good compiler which is sometimes lacking in the real work cough Scala cough. The problem with strong types and program proving is that the juice just isn't worth the squeeze meaning the extra time taken doesn't result in reduced debugging time or improved code quality. I don't think that changes with LLMs. It just exposes the flaws more quickly.
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That's literally the opposite of reality; the research and adoption have consistently produced code of extremely high quality, at great cost.
The problem has always been:
- It's extremely labour-intensive, and even small changes to the code can require an enormous amount of new proof work.
- The skills required to formally verify software are very different from the skills required to write it, and the set of people capable of doing so is much smaller.
- Code has to be written with verification in mind, against a specification that expresses invariants that can actually be verified, and that is coherent enough that you can derive useful high-level properties of the system from it.
You needed two teams — verification and development. Verification would always be behind the development team, while also having to feed requirements and design changes back to the developers. Everything slowed to a crawl.
AI changes this. A coherent, verifiable, useful specification isn't easy to write — but it's far easier to write than the software itself, and AI can do most of that work: both drafting the spec and proving that it's consistent and that the high-level properties you actually care about follow from it.
More importantly, a high-level spec is far easier to read and reason about than the reams of code required to actually implement something. Which means:
- AI does the grunt work of writing and proving the spec; humans only have to carefully review that high-level artifact.
- AI writes code it must also prove conforms to the spec, so humans can be assured it's correct without babysitting the AI.
- Changes are driven top-down: evolve the spec first, then have the AI fix the implementation and re-prove conformance.
Our (very, very large) company is rapidly going all-in on formal verification across projects we never would have dreamed of verifying before; the velocity hit and the man-hour cost were only worth paying for truly critical infrastructure.
what i expect to change with LLMs is the benefit you get from automated testing. which is really what LLMs need. tools that tell you something is wrong may not speed up a human developer, but they will allow LLMs to make corrections by itself until the warnings go away. so while it may not be worth it to a human developer, it may well be worth it for an LLM.
The issue with formal proofs is that we might end up with correct code that does the wrong thing. I mean, something that the market doesn't care about. At the same time a buggy set of PHP scripts does what people care about and captures the market. Think about 20+ years ago and you find a lot of examples.