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Book that teaches the method is here:

https://www.amazon.com/Toward-Defect-Programming-Allan-Stavely/dp/0201385953

It was a fun read. Mills and his people were brilliant in how they selectively adapted formal methods to programming for something semi-formal that was easy to learn and use by real programmers. One of early methods to truly engineer software (hence realengineering). For a few activities, there's automated tools now that look really similar to Stavely's methods. Some, like Frama-C, have been integrated into actual languages. So, I think whatever productivity and quality they had then would go up with modern tooling. On R&D side, combining it with functional language like Haskell along with its advanced typing might knock out even more problems. Give it instant execution like LISP and Smalltalk for exploratory phase where programmer hasn't determined correct behavior (i.e. specs) yet.

Cleanroom is still one of my favorite inventions in software. It's still ahead in defect rate of most stuff today. Only Praxis's Correct by Construction surpassed it for real-world programs but at much higher costs along various dimensions.



2 points by akkartik 499 days ago

I just bought this book.

Hillel Wayne's summarization of formal methods (https://www.laarc.io/item?id=663) has had a big effect on me, and a couple of days later Cleanroom sticks in my head as the #1 thing in this direction to learn more about.

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That's great to hear esp coming from you. You previously had no interest in these things if I recall correctly. There's a lot more to explore than most people think. Gaining more understanding, synthesis, partial/full verification, timing, flow, verified refactoring, parallelism/concurrency, and so on. As he describes, the formal methods might be there to do something for you, maybe just increase your own understanding, or something else. Most writings are strictly on formal, full correctness but field is broader than that.

Far as Stavely, I have the book in hand now. I think you'll find section 12.2 onward to be pretty inspiring. Since he's not in formal verification, he's not as biased in favor of throwing Isabelle and Coq at everything. His assessment of the past and future, at time of writing, is quite pragmatic. It's also still quite inspiring. Next step for anyone that learns Cleanroom to further assess its modern relevance is seeing how well it works with Haskell's typing, a LISP/Scheme, Smalltalk (or Strongtalk), and any language with Design-by-Contract (eg Ada/SPARK or D). I think a mix of semi-formal and formal contracts might emerge if programmer focuses on maximizing productivity and personal understanding over formality and proof. Some things will also just be tested because that might be easier.

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2 points by akkartik 498 days ago

Here's what I wrote you last March:

"I like math :) My pet peeve is just people overstating the use of existing formal methods. (Researching new ways to prove properties of programs is also great.)"

I think what got this post to have an effect was the clear-eyed acceptance of limitations, which in turn helped me see where they could actually help me today.

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Ok, I misremembered. I hear you. I originally got that from Guttman who focused on shredding claims of high-assurance security as much as verification. Others and I did submit a few things on limitations to Lobsters. They were general. I'll resubmit them to Laarc after I dig them up if you're interested. They might find them interesting, too.

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