prusti-dev VS tlaplus

> The overall goal would be to figure out classical error conditions like nill pointers deference.

> If I can figure out if a pointer will be nil in some execution branch, there is no reason why a computer cannot do the same.

Note, this is called flow-sensitive typing (also called type narrowing) and I think that typescript does it.

https://en.wikipedia.org/wiki/Flow-sensitive_typing

> I personally would see this as an human race level upgrades. Imagine feeding your code to a CI that spit back something like: "you will have a panic at line 156 when your input is > 4"

A model checker can do that!

See this

https://model-checking.github.io/kani/tutorial-kinds-of-fail...

Other techniques are also possible

https://github.com/viperproject/prusti-dev#quick-example

(Here I could link a lot of things, I just selected two Rust projects to illustrate)

This works better if you are able to provide contracts in your API that says which guarantees you provide. Alternatively, asserts are useful too.

You might be interested in the Prusti project, which statically checks for absence of reachable panics, overflows etc. It also allows user-defined specifications such as pre and post-conditions, loop body invariants, termination checking and so on.

https://github.com/viperproject/prusti-dev

This is called refinement types and prusti might be the project you saw.

But there's also a lot of exciting work around formal verification like Prusti.

prusti

Efforts: seL4, Project Everest, the Prossimo project of the ISRG, Let's Encrypt, and Prusti for the Rust language

Wow that sounds really cool! I'm not an expert but does that mean that one day you could implement dependend types or refinement types in Rust as a crate ? I currently only know of tools like: Flux Creusot Kani Prusti

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https://github.com/tlaplus/tlaplus/blob/master/tlatools/org....

In any case, our whole team thinks TLA is great, and we're happy people like you and Ron find it so useful and insightful. We also think it is a very insightful.

There are no tests! There are various ways to test concurrent data structures. You could use a stress test, where you spawn a lot of threads and let them mutate the map in a random way and then check the consistency of the map and some invariants. You could learn TLA+ and write a formal model of the map and then verify it.

Dafny and Whiley are two examples with explicit verification support. Idris and other dependently typed languages should all be rich enough to express the required predicate but might not necessarily be able to accept a reasonable implementation as proof. Isabelle, Lean, Coq, and other theorem provers definitely can express the capability but aren't going to churn out much in the way of executable programs; they're more useful to guide an implementation in a more practical functional language but then the proof is separated from the implementation, and you could also use tools like TLA+.

https://dafny.org/

https://whiley.org/

https://www.idris-lang.org/

https://isabelle.in.tum.de/

https://leanprover.github.io/

https://coq.inria.fr/

http://lamport.azurewebsites.net/tla/tla.html

I wish something like Lamport's TLA+ (https://lamport.azurewebsites.net/tla/tla.html) was supported in modern language compilers - perhaps with annotations/macros and a mini formal DSL.

Checking the invariant with assert is also useful in my limited experience with concurrency.

https://lamport.azurewebsites.net/tla/tla.html

One advantage of formal methods is in determining "what was expected" (including all the goofy edge cases) without having to burrow into the details of code.

Take a look at Alloy (http://alloytools.org/) and TLA+ (https://lamport.azurewebsites.net/tla/tla.html) for example. (Or even the ancient Z ("Zed") notation (https://www.cs.cmu.edu/~15819/zedbook.pdf)).

The pcal generator does *not* generate a definition for the set of labels. However, some users have suggested to add such a feature: https://github.com/tlaplus/tlaplus/issues/613