But Pascal was a small language. Getting this into today's bloated languages is tough. Back then, we looked at Ada, sized the project, and realized it was comparable to building an optimizing compiler for the language.
[1] http://www.animats.com/papers/verifier/verifiermanual.pdf
You sound like a very interesting person to buy a beer for, assuming you'd be patient enough for my questions :p, I'll check out the paper instead when I get the time.
> It's much easier to keep the verification statements correct if they're in the same file and the same language as the program.
Agreed. Hell even using Dialyzer in Erlang/Elixir for static type checking (which I make the effort to do often in my daily side project hacking) just doesn't feel right, even though it's still appended to function definitions in the original files.
This is one of those things that need to be a core part of the language design IMO, not just a tool built on top - 3rd party, by the core team, or otherwise. But, that said, tooling can still be superior compared to the complete absence of it.
Maybe you can answer a question I've been struggling to find the answer to via Google. Do you know the name of this popular older language/tool used by to Microsoft for doing formal verification? For c/c++ style code. It sounds like tkk or something similar? I can't seem to find it.
My other question I'd ask is if you think the testing analogy applies here as I mentioned in my comment above or do you see it as an entirely different paradigm? Basically changing how you program rather than adding on a tool/skillset.
I'd personally be excited too see a modern language implement this. I saw the potential for this type of verification in my (hobbyist) dabbling with Haskell. Which subsequently inspired me to relearn math, including a great book on proofs recommended on HN which really changed the way I viewed/approached math.
The use-case analogies for formal verification can probably best be drawn from automated testing and TDD. Which is another 'optional' part of programming with varying degrees of usage - although with a lower barrier to entry.
Types/proofs seem to have a positive influence on the 'best practice' part as well, as it promotes a programming style which force you to really consider the implementations you're coding. Very similar to testing.
At the moment formal proofs tools today seems to me like a rabbit hole with questionable practical ROI so I've been hesitant to try out the current state-of-the-art.
Assuming it does get built in to the language, even if it doesn't get used by the user they will likely benefit just by being able to build on layers beneath that were proven in the standard/popular libraries. I felt a similar feeling of assurance when building on top of well-typed Haskell libraries.