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What TLA+ can and can't check

243 points · 51 comments · b-man

  1. adamddev1 · · focus · HN ↗
    Great write-up. People keep saying "we can just write tests" or more recently "we can use formal verification," thinking these are sufficient safeguards we can use and then relegate all the implementation to LLMs. But the fact is that probabilistic guessing machines can't save them. People can't escape the need to actually understand the things they are building.
    1. rozap · · focus · HN ↗
      I recently had this discussion with an energetic junior coworker who just learned about TLA+ and thought it would solve all the problems. I think it probably did give the LLM that he was using to do the actual implementation a better starting off point, but the obvious gap remains, which is whether or not the spec (TLA) matches the implementation (elixir) which there's just not a good answer for. I encouraged him to put his TLA code in our docs folder, because as far as I'm concerned, it's just a suggestion, and then write (and understand...) some property tests about the feature.

      I think there probably is some value in vibecoding TLA specs and not actually understanding the invariants yourself, but it's way oversold by the talking heads of the tech world, and the gaps need to be filled in some other way if you refuse to write your own code.

      1. theknarf · · focus · HN ↗
        <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=ovlQ81rBc-4" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=ovlQ81rBc-4
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