eff
dafny
eff | dafny | |
---|---|---|
18 | 31 | |
546 | 2,763 | |
0.4% | 4.4% | |
0.0 | 9.7 | |
almost 1 year ago | 5 days ago | |
Haskell | C# | |
ISC License | GNU General Public License v3.0 or later |
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eff
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Haskellers who moved to Rust: What has been your experience?
You can swap-out implementations for testing, avoid the crazy N^2 instances issues, etc. They're pretty cool. Currently there are many competing libraries. polysemy and eff both have good examples on their homepages.
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What are the current hot topics in type theory and static analysis?
Effect systems and Algebraic effects. ocaml has just released a stripped-down effect system. People are also working on Effect systems for Haskell (eff, fused-effects, effet). Koka is a language built with effects first and foremost and it’s rapidly gaining popularity. Unison also has effects.
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[ANNOUNCE] GHC 9.6.1 is now available
There are also a few subtle issues that arise with delconts related to semantics of higher order effects (see here and here), but they might be solvable.
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Effectful | Paweł Szulc | Lambda Days 2022
Details are in https://github.com/hasura/eff/issues/12 and https://www.reddit.com/r/haskell/comments/pywuqg/unresolved_challenges_of_scoped_effects_and_what/.
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Looking for languages that combine algebraic effects with parallel execution
You'll get fearless parallel with STM in the mixture, and GHC is getting a work in progress effect system for Haskell, as Delimited continuation primops has been merged.
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Should I pick up OCaml or Haskell?
My last example is algebraic effects, some of which have been made possible in a both practical and efficient way thanks to extremely recent research, and that I can use to implement architectures like Ports and Adapters or Clean Architecture and have very maintainable code. (Extensible Effects — An Alternative to Monad Transformers was published in 2013, Effect Handlers in Scope was published in 2014 and they are behind Polysemy, while there is ongoing work on effects with even better performance, like Eff)
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[ANN] cleff - fast and consise extensible effects
cleff's Eff monad is esentially implemented as a ReaderT IO. [...] This is first done by eff, [...]
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Opinions on Reader + Continuation-based IO?
Here is link number 1 - Previous text "eff"
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Where's more discussion of the designs of effect systems?
Languages such as Koka only support algebraic effects, not scoping operations such as catch and listen. The Effect Handlers in Scope paper introduces scoping operations, which lead to the Haskell libraries fused-effects and polysemy, but they turned out to have some weird semantics. eff is her effort to fix that.
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Languages that don't support Error-Catching as a Control Structure?
There are a few languages that have algebraic effect systems, most notably Haskell, but these systems are implemented as libraries, not baked into the language (which can have advantages and disadvantages).
dafny
- Dafny is a verification-aware programming language
- Candy – a minimalistic functional programming language
- Dafny – a verification-aware programming language
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Lean4 helped Terence Tao discover a small bug in his recent paper
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
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The Deep Link Equating Math Proofs and Computer Programs
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
- The Dafny Programming and Verification Language
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In Which I Claim Rich Hickey Is Wrong
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
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Programming Languages Going Above and Beyond
> 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.
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What are the current hot topics in type theory and static analysis?
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 are some alternatives?
freer-simple - A friendly effect system for Haskell
tlaplus - TLC is a model checker for specifications written in TLA+. The TLA+Toolbox is an IDE for TLA+.
fused-effects - A fast, flexible, fused effect system for Haskell
FStar - A Proof-oriented Programming Language
frp-zoo - Comparing many FRP implementations by reimplementing the same toy app in each.
rust - Rust for the xtensa architecture. Built in targets for the ESP32 and ESP8266
in-other-words - A higher-order effect system where the sky's the limit
koka - Koka language compiler and interpreter
polysemy - :gemini: higher-order, no-boilerplate monads
Rust-for-Linux - Adding support for the Rust language to the Linux kernel.
extensible-effects - Extensible Effects: An Alternative to Monad Transformers
interactive - .NET Interactive combines the power of .NET with many other languages to create notebooks, REPLs, and embedded coding experiences. Share code, explore data, write, and learn across your apps in ways you couldn't before.