TOGVM-Spec VS dafny

Make each AST node an RDF node and then you can cram whatever information into it you want. That's the approach I've been taking with https://github.com/TOGoS/TOGVM-Spec/, anyway.

Of course, for conveniently and safely manipulating in memory in $programming_language, you're probably going to want to define some structs/ADTs/whatever that only contain the data a given compilation stage is actively working with.

I've been thinking that what I need is a system that allows me to quickly define different lower-level datatypes for representing different views of the conceptual types and automate, to some degree, translation between them, so then each part of the system can work with objects designed specifically to be processed by it with minimal fuss.

A technical reason for avoiding those specialized types might be that the computer then has to spend more time transforming from one schema to the next. I would think that in practice this isn't any worse than having to do a lot of null checks.

A more human reason is that it could bean a combinatorical explosion of AST types. I guess this is where my idea about lightweight variations comes in.

In TypeScript this kind of thing might not be so bad, since any object can be downcast with no cost to a type that contains a subset of the information, and variations on types can be easily defined without even necessarily being named, e.g. `ASTNode & HasResultType & HasSourceLocation`.

As far as graph-based languages and languages with arbitrary metadata and relationships between objects are concerned, I've been mulling over a language where expressions are represented as RDF graphs and that has built-in support for manipulating RDF graphs. I've use the concepts as an intermediate representation for functional expressions in a few different systems (including Factorio's map generator), but haven't yet had the motivation to really flesh it out into a full-blown language. https://github.com/TOGoS/TOGVM-Spec

For those that are interested but perhaps not aware in this similar project, Dafny is a "verification-aware programming language" that can compile to rust: https://github.com/dafny-lang/dafny

Code correctness is a lost art. I requirement to think in abstractions is what scares a lot of devs to avoid it. The higher abstraction language (formal specs) focus on a dedicated language to describe code, whereas lower abstractions (code contracts) basically replace validation logic with a better model.

C# once had Code Contracts[1]; a simple yet powerful way to make formal specifications. The contracts was checked at compile time using the Z3 SMT solver[2]. It was unfortunately deprecated after a few years[3] and once removed from the .NET Runtime it was declared dead.

The closest thing C# now have is probably Dafny[4] while the C# dev guys still try to figure out how to implement it directly in the language[5].

[1] https://www.microsoft.com/en-us/research/project/code-contra...

[2] https://github.com/Z3Prover/z3

[3] https://github.com/microsoft/CodeContracts

[4] https://github.com/dafny-lang/dafny

[5] https://github.com/dotnet/csharplang/issues/105

I don't think something that specific exists. There are a very large number of formal methods tools, each with different specialties / domains.

For verification with proof assistants, [Software Foundations](https://softwarefoundations.cis.upenn.edu/) and [Concrete Semantics](http://concrete-semantics.org/) are both solid.

For verification via model checking, you can check out [Learn TLA+](https://learntla.com/), and the more theoretical [Specifying Systems](https://lamport.azurewebsites.net/tla/book-02-08-08.pdf).

For more theory, check out [Formal Reasoning About Programs](http://adam.chlipala.net/frap/).

And for general projects look at [F*](https://www.fstar-lang.org/) and [Dafny](https://dafny.org/).

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 think we can assume it won't be as efficient has hand written code

Actually, surprisingly, not necessarily the case!

If you'll refer to the discussion in https://github.com/dafny-lang/dafny/issues/601 and in https://github.com/dafny-lang/dafny/issues/547, Dafny can statically prove that certain compiler branches are not possible and will never be taken (such as out-of-bounds on index access, logical assumptions about whether a value is greater than or less than some other value, etc). This lets you code in the assumptions (__assume in C++ or unreachable_unchecked() under rust) that will allow the compiler to optimize the codegen using this information.