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frank | FStar | |
---|---|---|
6 | 42 | |
253 | 2,562 | |
0.0% | 1.2% | |
0.0 | 9.9 | |
over 1 year ago | 5 days ago | |
Haskell | F* | |
GNU General Public License v3.0 only | Apache License 2.0 |
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Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
frank
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Do Be Do Be Do (2017) [pdf]
For the curious, "do be do be do" is a seminal paper in the literature on algebraic effects that introduces _frank_, quirky little language that has algebraic effects but not handlers, at least in the traditional sense.
Traditionally, an effect handler is an interpreter for a stream of commands, conforming to a specific interface. Generally, handlers surface in languages as a sort of generalized try/catch mechanism, that receive a "callback" to resume the "exception" that produced the command. In frank, not so.
Frank is based around the idea of _operators_, which generalize functions with the capability of interpreting multiple streams of commands. A plain function can be seen, in fact, as the special case of an operator that interprets no commands.
Operators are organized around ports and pegs. Pegs are the set of side effects that a computation needs. Each port is an offer to extend that set for downstream callers. Instead of building up a union of effects that each function needs, Frank propogated ambient ability inwards. Operators can then be composed based on the ports and pegs they offer.
operator: X → [peg]Y
This works partially because operators are shallow handlers and not deep handlers. Handlers interpret commands: if the handler itself is in scope when interpreting a command, then the language is said to have deep handlers. Frank has shallow handlers, meaning that commands are interpreted in an environment without the handling operator present. Shallow handlers give greater control to the programmer with respect to how commands are interpreted.
(This is a bad explanation because you already need to know what I'm talking about to understand what I'm talking about, but oh well.)
My one critism of frank is that the effect model is kinda hard for the working programmer to understand. I can explain Koka effects as "exceptions plus multiple resumption". I don't really have a categorical phrase for frank, and that's its innovation. This isn't so much a criticism but a plea for the pedagogical ramp to this research to improve.
do be do be do.
If you're still curious, check out the compiler github repo:
https://github.com/frank-lang/frank
And if anything is wrong in the above explanation, please correct me, because we all benefit from Cunningham's Law in the end. Allow me to be the fool.
- Efficient Compilation of Algebraic Effect Handlers - Ningning Xie
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Effekt, a research language with effect handlers and lightweight polymorphism
How does this compare to other effect-oriented languages like Koka, Frank, and Eff?
I've been doing some work with Koka lately, but I briefly looked into the other three (including Effekt) and it mostly came down to, 'Koka seems most active in development'[1] and 'Koka had the easiest to use documentation for me'[2].
[1] E.g. https://github.com/effekt-lang/effekt had its last commit back in June; https://github.com/frank-lang/frank last commit last year; but https://github.com/koka-lang/koka last update was Oct 15. Effekt seems semi-active, at least, compared to Frank. While stability is good, I wouldn't expect it in a language actively being used for research.
[2] Comparing https://koka-lang.github.io/koka/doc/book.html and https://effekt-lang.org/docs/ and https://www.eff-lang.org/learn/
- The Problem of Effects (2020)
- Extensible Effects in the van Laarhoven Free Monad
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What are some cool/wierd features of a programming language you know?
Frank's effect handling. "A strict functional programming language with a bidirectional effect type system designed from the ground up around a novel variant of Plotkin and Pretnar's effect handler abstraction. ... Frank [is different from other PLs with effect type systems in that it is based on] generalising the basic mechanism of functional abstraction itself. A function is simply the special case of a Frank operator that interprets no commands. Moreover, Frank's operators can be multihandlers which simultaneously interpret commands from several sources at once, without disturbing the direct style of functional programming with values. Effect typing in Frank employs a novel form of effect polymorphism which avoid mentioning effect variables in source code. This is achieved by propagating an ambient ability inwards, rather than accumulating unions of potential effects outwards."
FStar
- Lean4 helped Terence Tao discover a small bug in his recent paper
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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/).
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If You've Got Enough Money, It's All 'Lawful'
Don't get me wrong, there are times when Microsoft got it right the first time that was technically far superior to their competitors. Windows IOCP was theoretically capable of doing C10K as far back in 1994-95 when there wasn't any hardware support yet and UNIX world was bickering over how to do asynchronous I/O. Years later POSIX came up with select which was a shoddy little shit in comparison. Linux caved in finally only as recently as 2019 and implemented io_uring. Microsoft research has contributed some very interesting things to computer science like Z3 SAT solver and in collaboration with INRIA made languages like F* and Low* for formal specification and verification. But all this dwarfs in comparison to all the harm they did.
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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.
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Why is there no simple C-like functional programming language?
F* is a dependently typed language that can be transpiled to idiomatic C via the KReMLin compiler. It’s very ML-ish to write and you can leave out some proofs. It also has the benefit of being used to write a formally verified TLS implementation that’s in wide use throughout industry.
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[Media] Genetic algorithm simulation - Smart rockets (code link in comments)
As I said, dependent types attempt to solve this problem. F* is a language where you can express complex logic as a type. The catch is, these types are checked by an SMT solver. If the solver can satisfy the type checking, then great, and you move on. If it can’t, you have no idea why, and either have to guess or manually write the proof anyway. Contrast this with Standard ML which has a proof of the soundness of its type system.
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Prop v0.42 released! Don't panic! The answer is... support for dependent types :)
So kind of like F*? https://www.fstar-lang.org/
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old languages compilers
F*
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Pegasus spyware was used to hack reporters’ phones. I’m suing its creators; When you’re infected by Pegasus, spies effectively hold a clone of your phone – we’re fighting back.
Nevermind that academia has come up with far safer ways to do a few things but social norms & inertia prevent their wider adoption (well okay, it also has a barrier to entry in the education required to use it but I don't think someone with the knowledge to meaningfully contribute to an OS kernel can be considered uneducated nor unable to learn).
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[Hobby] Amateur Generalist Programmer Seeking to Put Bugfixing Skills to Good Use
Maybe that's a little off topic here, but if you like fixing bugs, i suspect you might also enjoy showing that there are no bugs at all. Check out languages like F* https://www.fstar-lang.org/ It's a proof-oriented programming language. You can use it to write code that has no bugs at all. And you once you're done, can convert F* to C or other languages.
What are some alternatives?
koka - Koka language compiler and interpreter
coq - Coq is a formal proof management system. It provides a formal language to write mathematical definitions, executable algorithms and theorems together with an environment for semi-interactive development of machine-checked proofs.
granule - A statically-typed linear functional language with graded modal types for fine-grained program reasoning
lean - Lean Theorem Prover
jellylanguage - Jelly is a recreational programming language inspired by J.
dafny - Dafny is a verification-aware programming language
effekt - A research language with effect handlers and lightweight effect polymorphism
gerty - A small implementation of graded modal dependent type theory. A younger cousin to Granule.
VisualFSharp - The F# compiler, F# core library, F# language service, and F# tooling integration for Visual Studio
eff - 🚧 a work in progress effect system for Haskell 🚧
stepmania - Advanced rhythm game for Windows, Linux and OS X. Designed for both home and arcade use.