Dafny Alternatives

dafny reviews and mentions

• Lean4 helped Terence Tao discover a small bug in his recent paper
  10 projects | news.ycombinator.com | 27 Oct 2023

  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

• The Deep Link Equating Math Proofs and Computer Programs
  5 projects | news.ycombinator.com | 11 Oct 2023

  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/).

• In Which I Claim Rich Hickey Is Wrong
  5 projects | news.ycombinator.com | 24 Jul 2023

  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

• Programming Languages Going Above and Beyond
  7 projects | news.ycombinator.com | 29 Jun 2023

  > 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.

  7 projects | news.ycombinator.com | 29 Jun 2023

  The language (Dafny): https://github.com/dafny-lang/dafny

  Dafny is a verification-ready programming language. As you type in your program, Dafny's verifier constantly looks over your shoulder, flags any errors, shows you counterexamples, and congratulates you when your code matches your specifications. When you're done, Dafny can compile your code to C#, Go, Python, Java, or JavaScript (more to come!), so it can integrate with your existing workflow.

• What are the current hot topics in type theory and static analysis?
  15 projects | /r/ProgrammingLanguages | 8 May 2023

  Most of the proof assistants out there: Lean, Coq, Dafny, Isabelle, F*, Idris 2, and Agda. And the main concepts are dependent types, Homotopy Type Theory AKA HoTT, and Category Theory. Warning: HoTT and Category Theory are really dense, you're going to really need to research them.

• What I've Learned About Formal Methods in Half a Year
  3 projects | news.ycombinator.com | 10 Apr 2023

  I'm not sure if the author is here, or if my comment attempt was successful. So, can I suggest you take a look at a third leg of the formal methods stool?

  If you are familiar with C, check out Frama-C (https://frama-c.com/) and the WP and RTE plugins. The approach is based on Tony Hoare and EWD's axiomatic semantics (https://en.wikipedia.org/wiki/Hoare_logic). It does not have a good memory management story, as far as I know, but is very good for demonstrating value correctness (RTE automatically generates assertions for numeric runtime errors, for example) and many memory errors.

  If you are familiar with Ada, check out SPARK (https://www.adacore.com/about-spark), which is similar to Frama-C but has a much better interface in the AdaCore GNAT toolkit and IDE.

  Both work similarly: Assertions in normal Ada or C code as well as the code itself are translated into SMT statements and fed to a SMT solver to find counterexamples---errors.

  I have some blog posts from several years ago about Frama-C:https://maniagnosis.crsr.net/tags/applied%20formal%20logic.h... (And I really should get back into it; it's a lot of fun.)

  If you are not familiar with Ada or C, Dafny (https://dafny.org/) is another option based on .NET and devoleped at Microsoft. It seems nigh-on perfect for this approach. (The language uses a garbage collector.) At the time I was looking, there was little documentation on Dafny, but that seems to have improved.

• Thoughts on proof assistants?
  4 projects | /r/ProgrammingLanguages | 13 Dec 2022

  But I suspect that will improve (they're all very new projects). I'm also keeping an eye on Dafny which looks pretty neat and avoids the "oh sorry we don't support traits" issue.

• What is the toughest concept to understand and implement in .NET according to you?
  3 projects | /r/dotnet | 28 Oct 2022

  However, if you want the full-fledged powerful code contacts back, you have to go outside C#. The closest you'll get is Dafny. It is a spec language that compiles to C#.

• There is framework for everything.
  107 projects | /r/ProgrammerHumor | 4 Aug 2022

  Most verification languages will do this. There are many of them but for something relatively easy to pick up, look at Dafny: https://github.com/dafny-lang/dafny

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