My “grand vision” for Rust

https://blog.yoshuawuyts.com/a-grand-vision-for-rust/

by todsacerdoti • 5 months ago

274 313 5 months ago

blog.yoshuawuyts.com

satvikpendem12• 5 months ago

Finally seeing more movement on effects or what started as keyword generics, there was a big blog post a few years ago but not much public facing news although of course they've been working on it as Yoshua says in the post.

I truly do wish we get closer to Ada and even Lean in terms of safety, would be great to see all these theoretical type system features become reality. I use the `anodized` crate right now for refinement type features, and who knows, maybe we get full fledged dependent types too as there aren't many production languages with them and certainly not popular languages.

pjmlp24• 5 months ago

Reposting my comment from Reddit,

I had some Scala 3 feelings when reading the vision, I hope Rust doesn't gets too pushy with type systems ideas.

That is how we end with other ecosystems doubling down in automatic memory management with a good enough ownership model for low level coding, e.g. Swift 6, OxCaml, Chapel, D, Linear Haskel, OCaml effects,...

Where the goal is that those features are to be used by experts, and everyone else stays on the confort zone.

satvikpendem12• 5 months ago

I doubt those languages would have the same level of traction as Rust, especially now that Rust has already gotten said traction over the past decade with even the Linux kernel using them. It's more likely that Rust will be written as today and then these extra features are added for more type safety in certain functions as like I said in another comment I doubt people are going to write type contracts for every single function (maybe LLMs will, but that's an orthogonal discussion).

pjmlp24• 5 months ago

Apparently you missed Swift.

Linux kernel adoption of Rust hasn't been a smooth ride, exactly because of its type system among C folks.

It is only happening because the likes of Google and Microsoft want to see it through.

Ygg23• 5 months ago

Doubt Rust will ever get to implicit hell of Scala 2.

If for anything, Rust isn't married to C as Scala is to Java.

pjmlp24• 5 months ago

It certainly is in what concerns ABI support, and dependency on LLVM.

Conscat2• 5 months ago

My understanding is that Scala 3 came with many large breaking changes that made adoption difficult. I at least hadn't heard users complain that new features weren't desired.

palata5• 5 months ago

I had some Scala 3 feelings when reading the vision, I hope Rust doesn't gets too pushy with type systems ideas.

I don't know if it is true or not, but my feeling is that Scala brought a lot of new ideas. But as I read somewhere, "Scala was written by compiler people, to write compilers", and I can understand that feeling.

Kotlin came after Scala (I think?) and seems to have gotten a lot of inspiration from Scala. But somehow Kotlin managed to stay "not too complex", unlike Scala.

All that to say, Rust has been innovating in the zero-cost abstraction memory safe field. If it went the way of Scala, I wonder if another language could be "the Kotlin of Rust"? Or is that Zig already? (I have no idea about Zig)

zozbot23411• 5 months ago

I wonder if another language could be "the Kotlin of Rust"?

Some people would say that Swift is that language since it's potentially memory safe like Rust and is described as friendlier to novices. There's some room for disagreement wrt. the latter point.

hocuspocus3• 5 months ago

But somehow Kotlin managed to stay "not too complex", unlike Scala.

It's not really true anymore, Kotlin has slowly absorbed most of the same features and ideas even though they're sometimes pretty half-baked, and it's even less principled than the current Scala ecosystem. JetBrains also wants to make Kotlin target every platform under the sun.

At this point, the only notable difference are HKTs and Scala's metaprogramming abilities. Kotlin stuck to a compiler plugin exposing a standard interface (kotlinx.serialization) for compile-time codegen. Scala can do things like deriving an HTTP client from an OpenAPI specification on the fly, by the LSP backend.

ozgrakkurt10• 5 months ago

This sounds insane at this point. The language already has too many features. Would be cool if all these people with amazing visions could move it elsewhere.

Rust is fast tracking being as bad as c++ in terms of just garbage in it.

IMO the worst thing about c++ isn't that it is unsafe but it is extemely difficult to learn to a satisfying degree.

This is already kind of feels true for Rust and it will be surely true if people just keep shoving their amazing ideas into it.

IMO even async/tokio/error-handling aren't that well though out in rust. So much for keeping things out of the language.

Maybe Rust just wasn't what I wanted and I am salty about it but it feels a bit annoying when I see posts like this and considering where Rust is now after many years of shoving stuff into it

fabiensanglard• 5 months ago

I agree that the complexity is getting scary. They keep on adding more and more stuff and it is hard to follow.

tcfhgj2• 5 months ago

Could you expand a bit more?

xiphias2• 5 months ago

The main problem I see is adding things slowly instead of automatic rewrites.

I remember adding lifetimes in some structs and then wanted to use generics and self pointing with lifetimes because that made sense, and then it didn't work because the composition of some features was not yet part of Rust.

Another thing: there are annotations for lifetimes in function signatures, but not inside the functions where there is a lot of magic happening that makes understanding them and working with them really hard: after finally the borrow checking gave me errors, that's when I just started to getting lots of lifetime errors, which were not shown before.

Rust should add these features but take out the old ones with guaranteed automatic update path.

satvikpendem12• 5 months ago

The edition mechanism covers your last paragraph.

zozbot23411• 5 months ago

The language already has too many features.

That's actually the point. Many of these additions can be phrased as unifying existing features and allowing them to be used in previously unusable ways and contexts. There's basically no real increase in user-perceived complexity. The Rust editions system is a key enabler of this, and C++ has nothing comparable.

pjmlp24• 5 months ago

It has clang tidy, -std=lang-version, and preprocessor that is version aware.

Rust editions don't cover all use cases that one can think of regarding language evolution, and requires full access to source code.

jstanley3• 5 months ago

https://xkcd.com/927/

patrick451• 5 months ago

This comparison is useless until rust commits to a stable ABI.

satvikpendem12• 5 months ago

It doesn't have too many features, it arguably does not have enough. The issue is that the current features don't play nicely with each other, so much of the work has been in making sure they do, such as with async traits as an example: there is no reason why you can make a function async but not inside a trait, and this was the case until very recently.

Beyond that, what the article shows is exactly what I want, I want as much type safety as possible especially for critical systems code which is increasingly what Rust is being used for.

LiamPowell3• 5 months ago

This inevitably happens when the approach to language design is "try it and see". I know people here hate design-by-committee, but historically it's led to some very cohesive languages.

SkiFire132• 5 months ago

Re: async in traits, the feature was delayed because it relied on the "Generic Associated Types" and "Impl Trait in Traits" features. If Rust delayed the whole `async` feature for working on those pretty type-theoretic features what would you have thought?

jcranmer• 5 months ago

You're not wrong here. Not that I'm entirely up-to-speed on all of the deep Rust discussions, but the sense I have of the language evolution is that while there is definitely a loud contingent of people pushing for a lot of the complexity of full effect systems or linear types, these sorts of proposals aren't actually all that likely to actually move forward in the language.

(I should note that of all of the features mentioned in this blog post, the only one I actually expect to see in Rust someday is pattern types, and that's largely because it partially exists already in unstable form to use for things like NonZeroU32.)

satvikpendem12• 5 months ago

Yoshua works directly on developing the language, and mentions he is working on these features specifically (he is part of the effects initiative), I'm not sure you won't see these features in Rust.

tcfhgj2• 5 months ago

What complexity?

selfmodruntime• 5 months ago

After working with Rust for half a decade I‘m afraid I have to agree. A lot of the newer features have weird edge cases with promises for fixes stuck in bikeshedding hell for years (looking at you const generics). Alternatively feature authors wait on dependecies that will never ship.

russdill• 5 months ago

I think part of the idea is you and to make it impossible to misuse an underlying API. This can make development much less complex.

arrty88• 5 months ago

I would love to have a use case to learn and write rust today. But i am deep in node and go services for my employer. Previously wrote java and c#. What are people writing in rust today?

satvikpendem12• 5 months ago

Whatever I used to use Node for, like web servers, I now use Rust. It's pretty nice, with a strong OCaml-like type system which I've used before (better than TypeScript even in some cases), plus it's much faster and more memory efficient such that I can run way more services on my 5 dollar Hetzner box with Dokploy compared to Node or Java or C#.

TeamDman• 5 months ago

I use Rust for command line applications.

I find that CLI is a great way to model problems. When I find myself doing something that has graduated beyond a comfortable amount of PowerShell, Rust is there for me.

I have a template I've been evolving so it's super easy to get started with something new; I just copy the template and slam Copilot with some rough ideas on what I want and it works out.

https://github.com/teamdman/teamy-rust-cli

Just today used it to replace a GitHub stats readme svg generator thing that someone else made that was no longer working properly.

https://github.com/TeamDman/teamy-github-readme-stats

Decomposes the problem very nicely into incrementally achievable steps

1. `fetch <username>` to get info from github into a cache location 2. `generate <username> <output.svg>` to load stats and write an svg 3. `serve` to run a webserver to accept GET requests containing the username to do the above

Means that my stuff always has `--help` and `--version` behaviours too

raphinou• 5 months ago

I'm working on a multisig sign-off solution, with the first use case being file downloads like GitHub releases authentication: https://github.com/asfaload/asfaload

I'm coming from F# and find rust a good compromise: great type safety (though I prefer the F# language) with an even better ecosystem. It can also generate decently sized statically compiled executables, useful for CLI tools, and the library code I wrote should be available to mobile apps (to be developed).

ChadNauseam3• 5 months ago

I'm having fun using it to make websites. Rust→WASM works really well. Definitely a very enjoyable way to make web apps. I've been trying to think how I can contribute to the ecosystem, seeing as I enjoy it so much. Rust gives you a control over memory that is impossible to replicate in javascript, and which allows much more performant code

wolvesechoes3• 5 months ago

What are people writing in rust today?

Rewriting existing code for karma points and GitHub stars. Plus some minority actually trying to build something new.

lsuresh2• 5 months ago

We built Feldera's engine in Rust: https://github.com/feldera/feldera

jadenPete• 5 months ago

I couldn’t disagree more. Most of my company’s backend code is written in Scala, and most of our engineers dislike it because the language is difficult to understand, has way too many features, and has many ways to solve the same problem. I don’t want Rust to continue down this path, and I already worry with some of the syntactic sugar and type system additions being discussed that it already has.

A language’s type system doesn’t need to model every possible type of guarantee. It just needs to provide a type safe way to do 95% of things and force its users to conform to use the constructs it provides. Otherwise it becomes a buggy hodge podge of features that interact in poor and unpredictable ways. This is already the case in Scala; we’ve discovered almost 20 bugs in the compiler in the past year.

satvikpendem12• 5 months ago

There is a middle ground. People seem to use Haskell and OCaml just fine and both are as expressive, so maybe it is just Scala having shoved in too many things. Based on what the article shows, it doesn't seem like they're making ten different ways to do the same thing but rather one way to (optionally) get more type safety out. I doubt everyone will be writing dependent type contracts for every single function, it's more for certain pieces of the codebase.

MrBuddyCasino2• 5 months ago

Ah yes Haskell, the reasonable centrist position in language design.

theknarf2• 5 months ago

A language’s type system doesn’t need to model every possible type of guarantee

Actually this is the exact point of a type system. Why would you want to write unit tests for stuff the compiler can guarantee for you at the type system level?

Animats2• 5 months ago

This may be too much advanced type theory for a useful language.

You can go all the way to formal verification. This is not enough for that. Or you can stop at the point all memory error holes have been plugged. That's more useful.

You can go way overboard with templates/macros/traits/generics. Remember C++ and Boost. I understand that Boost is now deprecated.

I should work some more on my solution to the back-reference problem in Rust. The general idea is that Rc/Weak/upgrade/downgrade provide enough expressive power for back references, but the ergonomics are awful. That could be fixed, and some of the checking moved to compile time for the single owner/multiple users case.

wofo• 5 months ago

Thanks for posting this! As a long-time Rust user (and contributor, in the good old days), the thing that has always fascinated me about Rust is the healthy balance it strikes between academic brilliance and industry pragmatism. Radical changes like the ones suggested by the OP risk damaging that balance IMO. I'd rather put up with some language quirks and see Rust achieve "boring technology" status...

But who knows, maybe the "academic brilliance" from the article is more pragmatic than I give it credit for. I sure hope for it if these changes ever go through.

tensor2• 5 months ago

How are these suggestions not pragmatic? You don't have to use them, but if you need them they are there. From a security point of view I can see many of these being incredibly useful.

Animats2• 5 months ago

The lack of use cases in that document is a concern. They're all "nice to have" features, but is the payoff there for real work? The "effects" section mentions properties useful for a proof system. But it's not part of a proof system. If it were, most of those could be found automatically by static analysis, without bothering the programmer. (I was doing that decades ago in a very early proof of correctness system.) Getting programmers to annotate items is tough. Just getting C++ programmers to use "const" enough is hard.

"View types" are interesting. But how much of that generality is really needed? We already have it for arrays, with "split_at_mut" and its friends. That's a library function which uses "unsafe" but exports a safe interface. The compiler will already let you pass two different fields of a struct as "&mut". That covers the two most pressing cases.

pjmlp24• 5 months ago

Boost is as actual as ever.

Also the way nowadays is with constexpr, templates, and around the corner, static reflection.

throwaway27448• 5 months ago

You can go way overboard with templates/macros/traits/generics.

You can go overboard on any language concept imaginable, but conflating all these mechanisms makes it sound like you haven't interacted much with non-C++ languages—particularly since rust doesn't have templates or anything like templates, traits are an entirely unrelated composition mechanism, and macros are entirely unrelated to the type discussion in the article.

This isn't really "advanced type theory" so much as picking up programming language developments from the 90s. I suppose it's "advanced" in the sense that it's a proper type system and not a glorified macro ala templating, but how is that a bad thing?

Cpoll• 5 months ago

Agreed. Generics are in most modern typed languages, and traits are essentially interfaces. Maybe templates means C++ templates, which are essentially generics?

Ygg23• 5 months ago

This may be too much advanced type theory for a useful language.

Maybe but:

- Move fixes Pin

- Linear types, prevent memory leaks

- potentially effects simplify so many things

Each of these functionalities unlock capabilities people have complained about Rust. Namely async, gen blocks, memory leaks.

jibal• 5 months ago

Yes. The appalling level of ignorance in the comments here and failure to understand the article is disturbing and a little scary ... hopefully it won't get in the way of actually simplifying and unifying the language, generalizing special cases, removing limitations and roadblocks, etc. as outlined in the article.

dnautics• 5 months ago

I'm not 100% convinced that "plugging memory error holes" was right at the compiler level.

Currently building out clr, which uses a heuristic (not formal verification) method for checking soundness of zig code, using ~"refinement types". In principle one could build a more formal version of what I'm doing.

https://github.com/ityonemo/clr

usrusr2• 5 months ago

Counterpoint: if any language could thrive in that valley of despair between pragmatic and theoretical excellence you're referring to, it would be Rust. Because so much of the cost is already paid for once you have satisfied the borrow checker. At least that's what I'd imagine, I could certainly be wrong.

Conscat2• 5 months ago

I understand that Boost is now deprecated.

Huh?? Boost is used basically everywhere.

Maxatar• 5 months ago

Not at all. Most of the good parts of boost are now part of the standard library, and the rest of boost that is of high quality have stand-alone implementations, like ASIO, pybind11 (which was heavily influenced by Boost.python), etc...

A lot of the new stuff that gets added into boost these days is basically junk that people contribute because they want some kind of resume padding but that very few people actually use. Often times people just dump their library into boost and then never bother to maintain it thereafter.

jandrewrogers2• 5 months ago

Definitely not. Boost is specifically prohibited in many companies. I haven’t run into Boost in a source tree in over a decade.

There are many reasons for this. Boost has uneven quality. Many of the best bits end up in the C++ standard. New versions sometimes introduce breaking changes. Recent versions of C++ added core language features that make many Boost library features trivial and clean to implement yourself. Boost can make builds much less pleasant. Boost comes with a lot of baggage.

Boost was a solution for when template metaprogramming in C++ was an arcane unmaintainable mess. Since then, C++ has intentionally made massive strides toward supporting template metaprogramming as a core feature that is qualitatively cleaner and more maintainable. You don’t really need a library like Boost to abstract those capabilities for the sake of your sanity.

If you are using C++20 or later, there isn’t much of a justification for using Boost these days.

riffraff• 5 months ago

This may be too much advanced type theory for a useful language.

I think a lot of things taken for granted these days were considered "too complicated" some time ago: think of how widespread pattern matching, closures, generics, or functional idioms in imperative languages are, and compare to e.g. Java 1.0.

My feeling is that the "acceptable level of complexity" for programming languages goes up over time, so probably stuff like effect types will be almost everywhere in another 10 years.

secondcoming2• 5 months ago

Boost is stronger than ever.

zamalek2• 5 months ago

I'm terrified by the notion of try fns. Are we getting exceptions (and therefore losing one of rust's greatest features)?

Pedro_Ribeiro• 5 months ago

Isn't his point exactly that we don't want to have too many function colors and instead want a generic way of declaring side effects so people can do what they want (be it try fns, IO, async, etc..., no panicking)?

zamalek2• 5 months ago

From the article:

And on nightly it also has support for try fn and gen fn.

I haven't been able to figure out what a try fn is.

pkal• 5 months ago

From the historical sources I could find online, it appears that Rust's borrow system was independently invented, or at least they don't mention linear logic or anything substructural. This is kind of interesting to me, especially given the reactions in this thread, and ties into the general difficulty of PL research to find acceptance among practitioners, especially when presented by researchers (which I think is regretful, I like the ideas in the article!). Perhaps we really should stick to terminology like "function colors" to make effect systems more popular (or not, because the color framing makes it sound bad to have different colors in a program, IIRC).

jltsiren• 5 months ago

It's the jargon, I think. PL research is in an awkward position, where the jargon is not shared with the much wider community of people using programming languages daily. From the other side, it looks like there is a small body of theoreticians using impenetrable language for discussing topics I'm supposed to be familiar with, because they are a core part of my day job. It's much easier to accept jargon, when it's used in a clearly separate field.

Some of the terminology is just unfortunate. For example, I have an intuitive understanding of what a type means. The meaning used in PL theory is somehow wider, but I don't really understand how.

And then there is my pet peeve: side effect. Those should be effects instead, because they largely define the observable behavior of the program. Computation, on the other hand, is a side effect, to the extent it doesn't affect the observable behavior.

But then PL theory is using "effect" for something completely different. I don't know what exactly, but clearly not something I would consider an effect.

voxl• 5 months ago

Man who uses arithmetic upset at research mathematicians for using words like R-module when they clearly do not mean a module in C++

More at 11

egorelik• 5 months ago

I don't remember where I read it, but I think Rust cited Cyclone as an influence, a variation of C with "region-based" memory management - more or less the literature name for "lifetimes". I think Rust may be the first to use it directly for stack variables, however.

DevelopingElk• 5 months ago

Rust's discussion boards has an idea of "keyword generics" for expressing some of these concepts. The idea is that a function can be generic over const, async or some other keyworded effect. I like this description. It shows the benefits without too much theory.

phplovesong• 5 months ago

async rust is the worse async out there. I prayed that rust did not include a async at all. But the JS devs pushed it thru. That pretty much sealed my rust use. Im still salty.

simonask6• 5 months ago

You know what, I’ve heard people say this and thought “OK, maybe these other languages with GCs and huge runtimes really do something magical to make async a breeze”.

But then I actually tried both TypeScript and C#, and no. Writing correct async code in those languages is not any nicer at all. What the heck is “.ConfigureAwait(false)”? How fun do you really think debugging promise resolution is? Is it even possible to contain heap/GC pressure when every `await` allocates?

Phooey. Rust async is doing just fine.

palata5• 5 months ago

How does it compare to Kotlin async? I find Kotlin generally hits a good balance across the board.

usrnm3• 5 months ago

Try golang, where they did the only sane thing: everything is async from the very beginning, no function colouring

mrsmrtss2• 5 months ago

In .NET 11 C# async management moved to the runtime, mostly eliminating heap allocations and also bringing clean stack traces. You really only need to think about ConfigureAwait(false) when building shared libraries or dealing with UI frameworks (even there you mostly don't need it).

pjmlp24• 5 months ago

Unless you are writing GUI code, ConfigureAwait() shouldn't be on your source code.

pjmlp24• 5 months ago

Not sure who pushed async Rust, but at least async JS does work without having to hunt down for runtimes, and naturally the answer is always Tokio.

VorpalWay7• 5 months ago

Usually the answer is embassy for me.

And embedded systems vastly outnumber classical computers. Every classical computer includes several microcontrollers, every car, modern appliance, camera, toy, etc does too. Safe languages for embedded and OSes is very important. Rust just happens to be pretty good for other use cases too, which is a nice bonus. But that means the language can't be tied to a single prescribed runtime. And that it can't have a GC, etc.

wewewedxfgdf• 5 months ago

No-one ever has the "Grand Vision" to cut something down to it's essential 25% and delete the rest.

techbrovanguard• 5 months ago

By all means, write some Go instead—you might want to order a new `if err != nil` button to stave off the RSI. The rest of us are trying to make things better.

ebiederm• 5 months ago

Chuck Moore of Forth fame.

lioeters• 5 months ago

Unless there's a conscious and constant effort to keep things simple, a programming language or software project will grow to consume all available resources, developers' time, intellectual capacity, and funding.

chiffaa3• 5 months ago

You can't cut down a language without breaking changes. And there fairly often are internal changes to simplify the compiler and the tooling. Just in the latest release, annotation internals were finally fully unified between rustc, cargo, clippy and other tools. This was a fairly considerable effort in deduplicating code. Borrow checker is being rewritten to move to tree borrows, trait resolution is being refactored for a variety of reasons. Code is being simplified where possible, but this doesn't mean Rust doesn't have areas to improve in, especially if there is a goal of replacing Ada/SPARK

nsm• 4 months ago

https://without.boats/blog/revisiting-a-smaller-rust/

I think there is a programming language hole for a Rust-like language, but with GC and green threads. One that dispenses with single-ownership, and async/await footguns.

Something like F#/Kotlin is closest in terms of developer experience.

Unfortunately, we are really lacking a language that skews badly on some other axis

- F# - tainted by being Windows only for really long and being Microsoft. - Kotlin - tainted by the JVM - Java 24+ - has virtual threads, sum types, match expressions and other niceties, but tainted by the JVM again (Verbosity included, but this is not really a factor with IDEs and LLMs.)

Note that the opinions above are not mine, but "consensus". I'd say they are all unfair opinions.

I feel like people end up favoring new languages, simply because of novelty. Like, inevitably, somebody is gonna say Gleam. I'm all for having existing BEAM users getting access to new languages, but I'm not sure why one would pick a BEAM language for non-server applications when the developer tooling story for CLI apps, line-of-business apps and so on is so much stronger for the .NET and JVM ecosystems. No offense to the Gleam folks intended.

plantain• 5 months ago

I used to hate Golang for not having generics and how verbose getting basic things done was. Then I read posts like this and realise, my god, Rob Pike was so, so right.

Do these people ever ship anything? Or is it just endless rearranging of deckchairs?

beanjuiceII• 5 months ago

I already need a reference to read rust code, looks like I'll need a third reference sheet. The language is currently bordering on spaghetti

ozgrakkurt10• 5 months ago

The most annoying part is that you can't just go to source code or docs and understand some code. I still can't do it after spending many years using it. You have to wade through 7 layers of macros and traits to understand some basic thing most of the time.

It is easier to understand musl-libc code compared to understanding a http library in rust which is just insane to me.

pjmlp24• 5 months ago

I mostly agree, however it wouldn't harm Go, even to get back some of the niceties of Limbo that it still misses.

conorbergin2• 5 months ago

Thank God for Zig

esafak2• 5 months ago

Elaborate.

conorbergin2• 5 months ago

I don’t think PL theory driven design produces good systems languages.

pjmlp24• 5 months ago

For bringing us back to Modula-2?

QuantumNoodle4• 5 months ago

I write production Rust code that becomes critical infra for our customers. I got tired of nil checks in Go and became a squeaky wheel in incident retros, where I finally got the chance to rewrite parts of our system in Rust during a refactor.

I admit the skill issue on my part, but I genuinely struggled to follow the concepts in this article. Working alongside peers who push Rust's bleeding edge, I dread reviewing their code and especially inheriting "legacy" implementations. It's like having a conversation with someone who expresses simple thoughts with ornate vocabulary. Reasoning about code written this way makes me experience profound fatigue and possess an overwhelming desire to return to my domicile; Or simply put, I get tired and want to go home.

Rust's safety guardrails are valuable until the language becomes so complex that reading and reasoning about _business_ logic gets harder, not easier. It reminds me of the kid in "A Christmas Story" bundled so heavily in winter gear he cant put his arms down[0]. At some point, over-engineered safety becomes its own kind of risk even though it is technically safer in some regards. Sometimes you need to just implement a dang state machine and stop throwing complexity at poorly thought-through solutions. End old-man rant.

[0] https://youtu.be/PKxsOlzuH0k?si=-88dxtyegTxIvOYI

QuaternionsBhop• 5 months ago

Reasoning about code written this way makes me experience profound fatigue and possess an overwhelming desire to return to my domicile;

I didn't understand that you were making fun of verbosity until the word 'domicile'. I must be one of those insufferable people who expresses simple thoughts with ornate vocabulary...

The article was comprehensible to me, and the additional function colorings sound like exciting constraints I can impose to prevent my future self from making mistakes rather than heavy winter gear. I guess I'm closer to the target audience?

baby• 5 months ago

I really think that golang makes it easy to read code, rust makes it easy to write code. If Golang had sum types it would be a much nicer language to write complex applications with

nine_k2• 5 months ago

Golang makes easy-to-skim code, with all the `if err != nil` after every function call.

Rust requires actual reading, like Typescript, only more detailed.

haileys• 5 months ago

I find Go code mind numbing to read. There's just _so much of it_ that the parts of the code that should jump out at me for requiring greater attention get lost in the noise. Interfaces also make reading Go more difficult than it could be without LSP - there's no `impl Xyz for` to grep for.

9rx5• 5 months ago

Go does have sum types — but the syntax is awkward and a bit transparent, so many don't recognize it as being there, and those that do don't love using it.

umanwizard5• 5 months ago

Go makes it easy to read each line of code, not necessarily to understand what the system as a whole is doing.

nemothekid• 5 months ago

I've been on both sides of the fence here - I've bounced between two camps:

1. Go with a better type system. A compiled language, that has sum types, no-nil, and generics.

2. A widely used, production, systems language that implements PL-theory up until the year ~2000. (Effects, as described in this article, was a research topic in 1999).

I started with (1), but as I started to get more and more exposed to (2), you start looking back on times when you fought with the type system and how some of these PL-nerds have a point. I think my first foray into Higher-Kinded Types was trying to rewrite a dynamic python dispatch system into Rust while keeping types at compile time.

The problem is, many of these PL-nerd concepts are rare and kind of hard to grok at first, and I can easily see them scaring people off from the language. However I think once you understand how they work, and the PL-nerds dumb down the language, I think most people will come around to them. Concepts like "sum types" and "monads", are IMO easy to understand concepts with dumb names, and even more complex standard definitions.

kelipso• 5 months ago

Yeah, (non sarcastically) give those things dumb names like borrow checker and you'll get people swooning over it.

Horusiath• 5 months ago

1. Go with a better type system. A compiled language, that has sum types, no-nil, and generics.

I was looking for something like that and eventually found Crystal (https://crystal-lang.org) as a closest match: LLVM compiled, strong static typing with explicit nulls and very good type inference, stackfull coroutines, channels etc.

sam0x172• 5 months ago

I feel you, but hear me out. OP is right. I've wanted pretty much everything he's talking about here for years, I just never thought of all of this in as quite a formal way as he has. We need the ability to say "this piece of code can't panic". It's super important in the domains I work in. We also need the ability to say "this piece of code can't be non-deterministic". It's also super important in the domains I work in. Having language level support for something like this where I add an extra word to my function def and the compiler guarantees the above would be groundbreaking

chirsz• 5 months ago

You can see:

* no-panic: https://docs.rs/no-panic/latest/no_panic/

* Safe Rust has no undefined behavior: https://news.ycombinator.com/item?id=39564755

rapnie4• 5 months ago

Perhaps there are similarities to Scala, from my anecdotal observation. Coming from Java and doing the Scala coursera course years ago, it feels like arriving in a candy shop. All the wonderful language features are there, true power yours to wield. And then you bump into the code lines crafted by the experts, and they are line for line so 'smart' they take a real long time to figure out how the heck it all fits together.

People say "Rust is more complex to onboard to, but it is worth it", but a lot of the onboarding hurdle is the extra complexity added in by experts being smart. And it may be a reason why a language doesn't get the adoption that the creators hoped for (Scala?). Rust does not have issues with popularity, and the high onboarding barrier, may have positive impact eventually where "Just rewrite it in Rust" is no more, and people only choose Rust where it is most appropriate. Use the right language for the tool.

The complexity of Rust made me check out Gleam [0], a language designed for simplicity, ease of use, and developer experience. A wholly different design philosophy. But not less powerful, as a BEAM language that compiles to Erlang, but also compiles to Javascript if you want to do regular web stuff.

[0] https://gleam.run

awesan2• 5 months ago

IMO rust started at this from the wrong direction. Comparing to something like zig which just cannot panic unless the developer wrote the thing that does the panic, cannot allocate unless the developer wrote the allocation, etc.

Rust instead has all these implicit things that just happen, and now needs ways to specify that in particular cases, it doesn't.

QuantumNoodle4• 5 months ago

I have no argument against using the right tool for a job. Decorating a function with a keyword to have more compile-time guarantees does sound great, but I bet it comes with strings attached that affect how it can be used which will lead to strange business logic. Anecdotally, I have not (perhaps yet) run into a situation where I needed more language features, I felt rust had enough primatives that I could adapt the current feature set to my needs. Yes, at times I had to scrap what I was working on to rewrite it another way so I can have compile-time guarantees. Yes, here language features offer speed in implementing.

Could you share a situation where the behavior is necessary? I am curious if I could work around it with the current feature set.

Perhaps I take issue with peers that throw bleeding edge features in situations that don't warrant them. Last old-man anecdote: as a hobbyist woodworker it pains me to see people buying expensive tools to accomplish something. They almost lack creativity to use their current tools they have. "If I had xyz tool I would build something so magnificent" they say. This amounts to having many, low-quality single-purpose built tools where a single high-quality table saw could fit the need. FYI, a table-saw could suit 90% of your cutting/shaping needs with a right jig. I don't want this to happen in rust.

olalonde2• 5 months ago

Can we get a version of Rust that swaps lifetimes and ownership for a GC and a JS-style event loop? I love the DX of the language, but I don't always need to squeeze out every microsecond of performance at the cost of fighting the borrow checker.

pharrington• 5 months ago

https://ocaml.org/

widdershins• 5 months ago

https://gleam.run

secondcoming2• 5 months ago

Then why are you using rust for these tasks?

harpiaharpyja2• 5 months ago

I mean, you're asking for a fundamentally different directing for the language with different tradeoffs? Why are you commenting on an article about Rust? Not everyone wants the same tradeoffs that you do.

andriy_koval4• 5 months ago

I love the DX of the language, but I don't always need to squeeze out every microsecond of performance at the cost of fighting the borrow checker.

you can use smart pointers everywhere and stop be bothered by borrow checker.

rob74• 5 months ago

I experienced the same kind of fatigue when I read "there are three directions of development which I find particularly interesting: [three things I never heard about nor particularly want to get familiar with]" in the article.

And later, when I read "Because though we’re not doing too bad, we’re no Ada/SPARK yet" I couldn't help thinking that there must be a reason why those languages never became mainstream, and if Rust gets more of these exciting esoteric features, it's probably headed the same way...

gignico3• 5 months ago

I think the misunderstanding here is that the article was not intended to users but to other language designers.

As a user, using a feature such as pattern types will be natural if you know the rest of the language.

Do you have a function that accepts an enum `MyEnum` but has an `unreachable!()` for some variant that you know is impossible to have at that point?

Then you can accept a `MyEnum is MyEnum::Variant | MyEnum::OtherVariant` instead of `MyEnum` to tell which are the accepted variants, and the pattern match will not require that `unreachable!()` anymore.

The fact someone does not know this is called "refinement types" does not limit their ability to use the feature effectively.

thomasmg6• 5 months ago

the article was not intended to users but to other language designers.

That might be true, but it shows the direction that Rust is talking: put in the kitchen sink, just like C++ and Scala did. And _that_ is very much important for users.

ajxs• 5 months ago

At the risk of sounding like a language zealot, have you ever looked at Ada? It was explicitly designed to be very readable, and for use in safety-critical systems. Ada isn't perfect in all the ways Rust isn't, and it might not be the right choice for your system, but if you're writing systems software it's worth a look. If you're writing a web backend on the other hand, it's not worth a look at all.

9rx5• 5 months ago

Unless you are going back to CGI, web backends are systems.

tormeh• 5 months ago

Nothing can really save you from architecture astronauts, except possibly Go, but I hear there are people templating Go with preprocessors, so who knows. This is a human problem. On the other hand I hear you. The moment Rust gets proper async traits an entire world of hexagonal pain will open up for the victims of the astronauts. So it will get even worse, basically. I think if we could solve the problem of bored smart people sabotaging projects it'd be amazing.

63stack• 5 months ago

I don't think this is an old man rant, I think you made a reasonable argument. Rust is certainly at risk of becoming just as complex as c++.

I would love to introduce more rust at work, but I dread that someone is going to ask about for<'a>, use<'a>, differences between impl X vs Box<dyn X>, or Pin/Unpin, and I don't have proper answers either.

andriy_koval4• 5 months ago

but I dread that someone is going to ask about for<'a>, use<'a>, differences between impl X vs Box<dyn X>, or Pin/Unpin, and I don't have proper answers either.

its an issue in "someone", all those answers can be received in under 1min from AI.

devnullbrain2• 5 months ago

A state machine is a perfect example of a case where you would benefit from linear types.

Some things just need precise terminology so humans can communicate about them to humans without ambiguity. It doesn't mean they're inherently complex: the article provides simple definitions. It's the same for most engineering, science and language. One of the most valuable skills I've learned in my career is to differentiate between expressions, statements, items, etc. - how often have you heard that the hardest problem in software development is coordinating with other developers? If you learn proper terminology, you can say exactly what you mean. Simple language doesn't mean more clear.

I wasn't born knowing Rust, I had to learn it. So I'm always surprised by complaints about Rust being too complex directed at the many unremarkable people who have undergone this process without issues. What does it say, really? That you're not as good as them at learning things? In what other context do software people on the internet so freely share self-doubt?

I also wonder about their career plans for the future. LLMs are already capable of understanding these concepts. The tide is rising.

kibwen4• 5 months ago

I genuinely struggled to follow the concepts in this article

I read the HN comments before I read the OP, which made me worry that the post was going to be some hifalutin type wonkiness. But instead the post is basically completely milquetoast, ordinary and accessible. I'm no type theorist--I cannot tell you what a monad is--and I confess that I don't understand how anyone could be intimidated by this article.

Folcon• 5 months ago

I think you're underestimating your competency

Things like effects aren't obvious to people, at least based on my experience of trying to teach it to people

dilawar• 5 months ago

I got tired of nil checks in Go and became a squeaky wheel in incident retros, where I finally got the chance to rewrite parts of our system in Rust during a refactor.

At a new job, I am writing my first microservice in golang. Used to be a Rust/C++ (kernel) and Python/PHP/JS dev (fullstack). Rust is allowed by team is heavily invested in go already.. I don't think I'll be able to convince them to learn rust! Lol

harpiaharpyja2• 5 months ago

Look, included in the concepts the article discusses are features that people have been wanting for a very long time.

Like, the ability to have multiple mut references to a struct as long as you access disjoint fields? That's amazing!!! A redo of Pin that actually composes with the rest of the language? That's pretty awesome too.

I think you're getting tied up because the the author is describing these features in a very formal way. But someone has to think about these things, especially if they are going to implement them.

Ultimately, these are features that will make Rust's safety features (which really, are Rust's reason for existing) more ergonomic and easier to use. That's the opposite of what you fear.

keybored• 5 months ago

Rust is complex enough as-is. There is definitely a learning curve.

But these top-comments sometimes paint with a broad brush. As in this case.

I admit the skill issue on my part, but I genuinely struggled to follow the concepts in this article. Working alongside peers who push Rust's bleeding edge, I dread reviewing their code and especially inheriting "legacy" implementations. It's like having a conversation with someone who expresses simple thoughts with ornate vocabulary. Reasoning about code written this way makes me experience profound fatigue and possess an overwhelming desire to return to my domicile; Or simply put, I get tired and want to go home.

Two paragraphs in and nothing concrete yet. We can contrast with the article. Let’s just consider the Effects section.

It describes four examples: functions that 1) don’t unwind, 2) guaranteed termination, 3) are deterministic 4) do not “call host APIs”, which is “IO” somehow? (this last one seems a bit off)

The first point is about not panicking (keyword panic given). Point two is about not looping forever, for example. Point three can be contrasted with non-determinism. Is that jargony? A fancy-pants term for something simpler? The fourth point seems a bit, I don’t know, could be rewritten.

All of these at least attempt to describe concrete things that you get out of an “effects system”.

Rust's safety guardrails are valuable until the language becomes so complex that reading and reasoning about _business_ logic gets harder, not easier. It reminds me of the kid in "A Christmas Story" bundled so heavily in winter gear he cant put his arms down[0]. At some point, over-engineered safety becomes its own kind of risk even though it is technically safer in some regards. Sometimes you need to just implement a dang state machine and stop throwing complexity at poorly thought-through solutions. End old-man rant.

This is just a parade of the usual adjectives with an unexplained analogy thrown in (how will these additions cripple Rust usage?). “So complex”, “over-engineered safety”, “complexity” (again), “poorly thought-throught solutions”.

TFA is about concrete things. OP here is a bunch of adjectives. And a bunch of words about complexity and not understanding would be fine if TFA did not have any understandable, practical parts. But as we’ve gone over it does...

People see Rust. Then they see a comment reacting to nondescript complexity. The rest is history.

A good anti-complexity comment would address something concrete like Async Rust. And there are plenty of such comments to vote on.

nine_k2• 5 months ago

As I was getting into computers as a teenager, a teacher warned me that the area is such that I would have to learn new things constantly, without end. I said, fine, what's not to like?

But I now realize that as people grow, their desire to learn new things sometimes fades, and an illusion of "already knowing enough" may set in.

Don't trust that illusion. We still have to learn new things every day. (And new fancy words for simple concepts is the easy part.)

jbritton2• 5 months ago

When I wrote my very first Rust code, I was trying to write to a socket. I got stuck on this task with misleading error messages for the longest time. I finally realized I had not made the socket object mutable. I’m used to Posix where you have an integer file descriptor and I don’t tend to think of socket write as a mutable operation. At least it doesn’t mutate state that my app manages. Perhaps something in the kernel gets mutated. I believe the socket interface may have been intended to support queuing which is perhaps why it needed to be mutable. I might have needed a lower level api. I just mention this because I think it’s interesting as to how it should be typed when mutation is external to the app. I didn’t follow through on using Rust and this was long ago so I’m sure some details are wrong.

holden_nelson• 5 months ago

I also found it really unintuitive what needs to be made mutable. And still do to some degree.

When I first had learned that rust had this concept of “opt-in” mutability, I thought that it must then be an accepted pattern that we make as little as possible be mutable in an attempt to help us better reason about the state of our program. I had come to rust after learning some clojure so I was like “ahh! Immutable by default! So everything’s a value!”

But in reality it feels like rust code is not “designed” around immutability but instead around appeasing the borrow checker - which is actually pretty easy to reason about once you get the hang of the language. But it’s a ton to learn up front

estebank2• 5 months ago

got stuck on this task with misleading error messages for the longest time.

Could you elaborate on that? We consider misleading error messages to be bugs and would like to know more on case we could fix them.

jbritton2• 4 months ago

It appears the error message has been improved.

undeveloper2• 5 months ago

I think part of it might be just that for modeling's sake it makes it clear when something can write vs only read the socket

scottlamb• 5 months ago

`std::net::TcpStream`? Interestingly, it doesn't need to be mutable if you know the trick.

* It implements `Write` for `TcpStream` which is likely what you were using. And `Write` requires `&mut`, probably because the same trait is used for writing to application buffers (e.g. through `BufWriter` or just to a `Vec`). So this doesn't compile: [2] I think the error message is pretty good; maybe it's improved since you tried. It doesn't though suggest the trick below.

* It also implements `Write` for `&TcpStream`. So if you use the awkward phrasing `(&stream).write_all(b"asdf")`, you don't need mutable access. [3] This allows you to use it with anything that takes the trait, without requiring mutability. You might need this if say you're reading from the socket from one thread while simultaneously writing to it from another thread.

It's a vaguely similar situation with the most common async equivalent, `tokio::net::TcpStream`. The most straightforward way to write to it is with a trait that needs mutable access, but it is possible to write to a shared reference by not using a trait. They also have these `split` and `into_split` methods to get mutable access to something that implements the read traits and something that implements the write traits.

[1] https://doc.rust-lang.org/std/net/struct.TcpStream.html

[2] https://play.rust-lang.org/?version=stable&mode=debug&editio...

esafak2• 5 months ago

These would be great additions. I don't get why people don't want powerful type systems. Let the language work for you!

hardwaresofton2• 5 months ago

Really excited for the possibilities here.

People undoubtedly thought going for Affine types was too much, and even simple things like null safety or enums-with-values and the prevalence of Result saw debate with minimalists voicing concerns.

A world where you could write a Rust program that is memory leak free with Affine types is one I want to live in. Haskell can do it now, but its just not easy and Rust has beat out Haskell with its mix of ML-strength types and practicality.

IMO these changes maintain Rusts winning mix of academia and practicality. Heres a proof point — dependent types weren't mentioned :)

hardwaresofton2• 5 months ago

*linear types (the leak free future bit)

This description is also a good crystallization of why one would want linear types

pornel• 5 months ago

It's hard to see features through the programming language theory jargon, but solid theoretical foundations have worked well for Rust so far.

Jargon terms like "sum types" or "affine types" may seem complicated, but when you see it's actually "enums with data fields", it makes so much sense, and prevents plenty of state-related bugs.

Proposed "effects" mean that when you're writing an iterator or a stream, and need to handle error or await somewhere in the chain, you won't suddenly have a puzzle how to replace all of the functions in the entire chain and your call stack with their async or fallible equivalents.

"linear types" means that Rust will be able to have more control over destruction and lifetime of objects beyond sync call stack, so the tokio::spawn() (the "Rust async sucks" function) won't have to be complaining endlessly about lifetimes whenever you use a local variable.

I can't vouch for the specifics of the proposed features (they have tricky to design details), but it's not simply Rust getting more complex, but rather Rust trying to solve and simplify more problems, with robust and generalizable language features, rather than ad-hoc special cases. When it works it makes the language more uniform overall and gives a lot of bang for the buck in terms of complexity vs problems solved.

ozgrakkurt10• 5 months ago

What worked for rust is having enums, sane-ish error handling, having sane integer types and the borrow checker, good tooling. The rest is just not that useful compared to how much garbage it creates

ChadNauseam3• 5 months ago

You didn't mention parametric polymorphism, which is incredibly useful and important to the language. I'm guessing you intentionally excluded async, but to describe it as "not that useful" would just be wrong, there is a large class of programs that can be expressed very simply using async rust but would be very complicated to express in sync rust (assuming equivalent performance).

undeveloper2• 5 months ago

I'm not sure why people are so deeply scared. these are all pretty neat features for people who will need them (off rip seemingly mostly in the embedded world). It's not like the inclusion of these forces you to use them — I've never had to deal with unsafe rust for shipping web stuff, and I highly doubt I'd have to deal with most of these. For modeling's sake it would be nice to have pattern types and view types, I can see them being useful

simplesocieties2• 5 months ago

This was the exact same argument used to push new c++ features and look where the language is now.

devnullbrain2• 5 months ago

...a far better place than 2011.

gpderetta• 5 months ago

you mean better than ever?

ozgrakkurt10• 5 months ago

People will push this crap into production codebases and link to these articles when you say you don’t want complexity. Best way to manage is to not make it possible, like go.

You indirectly deal with this kind of thing when compiling web server code too. It compiles super slow and can have weird errors. This is because the people who build the web stack in rust used a million traits/generics/macros etc.

Even if you look at something like an io_uring library in rust, it uses a bunch of macros instead of just repeating 3 lines of code.

anon291• 5 months ago

3 lines of code that may need to change is much more complex than a macro that signals intent.

simplesocieties2• 5 months ago

The rust maintainers need to learn from the mistakes of the c++ design committee and understand that not adding a feature at all is in itself a desirable feature.

For example, your section on effects:

Functions which guarantee they do not unwind (absence of the panic effect)

* I actually don’t see how this is any more beneficial than the existing no_panic macro https://docs.rs/no-panic/latest/no_panic/

Functions which guarantee they terminate (absence of the div effect)
Functions which are guaranteed to be deterministic (absence of the ndet effect)
Functions which are guaranteed to not call host APIs (absence of the io effect)

The vast majority of rust programs don’t need such validation. And for those that do, the Ferrocene project is maintaining a downstream fork of the compiler where this kind of feature would be more appropriate.

I think rust is in a perfect spot right now. Covers 99.99% of use cases and adding more syntax/functionality for 0.001% of users is only going to make the language worse. The compiler itself provides a powerful api via build.rs and proc macros which let downstream maintainers build their desired customization.

ozgrakkurt10• 5 months ago

You just know some guy will try to make cli code no-panic/deterministic use a bunch of crap and think he achieved something.

Just not allowing complex code is so much better than this.

Just even being able to look at a piece of code and trace what it is doing is 1000x more valuable than this. I regretted almost every time I allowed Traits/generics into a codebase

chiffaa3• 5 months ago

There are ways to handle these effects without bloating up normal applications. For example, using attributes implemented as intrinsics, which wouldn't really affect anything that isn't using them.

The thing is, some of these things are very useful in specific domains, and all these domains are closely related to the ideas of safety. Nondeterminism and IO are important for purity/referential transparency, which is a fairly important effect for business logic IMO. Guaranteed termination matters for formal verification. Unwind removal matters for embedded. I don't think wishing for these things is really all that unwarranted

I actually don’t see how this is any more beneficial than the existing no_panic macro

no_panic and similar macros are doing a very hacky workaround which isn't really a great static guarantee. The simple fact that building with panic = abort makes the macro useless is an annoyance in and of itself. dtolnay did great when figuring out some path forward but it's somewhat shaky

dtolnay2• 5 months ago

If a piece of code does not panic in panic=unwind, then it does not panic in panic=abort either. So having coverage of panic=unwind would be sufficient to guarantee that code cannot panic. The caveat you mention with panic=abort would only apply to code that is unable to build for panic=unwind, which is uncommon.

aw162110710• 5 months ago

I actually don’t see how this is any more beneficial than the existing no_panic macro

I think looking at the caveats listed in the no_panic docs should give you some ideas as to how a "proper" no_panic effect could improve on the macro.

Furthermore, a "proper" effect system should make working with effects nicer in general - for instance, right now writing functions that work independently of effects is not particularly ergonomic.

The vast majority of rust programs don’t need such validation.

I think you also need to consider the niches which Rust wants to target. Rust is intended to be usable for very low-level/foundational/etc. niches where being able to track such effects is handy, if not outright required, so adding such support would be unblocking Rust for use in places the devs want it to be usable in.

And for those that do, the Ferrocene project is maintaining a downstream fork of the compiler where this kind of feature would be more appropriate.

Given this bit from the Ferrocene website:

Ferrocene is downstream from Rust
It works with existing Rust infrastructure and the only changes made in the code were to cover testing requirements of ISO 26262, IEC 61508 and IEC 62304 qualification. All fixes are reported upstream for constant improvement.

I would suspect that such changes would be out of scope for the Ferrocene fork because that fork is more intended to be a qualified/certified Rust more than Rust + completely novel extensions.

The compiler itself provides a powerful api via build.rs and proc macros which let downstream maintainers build their desired customization.

Given the complexity of the features listed this feels tantamount to asking each individual consumer to make their own fork which doesn't seem very likely to attract much interest. IIRC async even started off like that (i.e., using a macro), but that was painful enough and async thought to be useful enough to be promoted to a language feature.

I'm curious to what extent one can implement the described features using just build.rs/proc macros in the first place without effectively writing a new compiler.

krautsauer• 5 months ago

The "caveats" section in its docs hints at it, but to be explicit: no_panic is a band-aid that can break when changing optimizer options or compiler/llvm version. It's not a good option for library crates, e.g.

That being said, I'm not at all happy with all the complexity and ecosystem fragmentation that async brought. I understand what you're saying. But surprise panics is a bit of a pain point for me.

dtolnay2• 5 months ago

It's not a good option for library crates, e.g.

Author here. Yes, it is. It was literally made for libraries. Notably https://github.com/dtolnay/zmij and https://github.com/dtolnay/itoa use it to enforce that the libraries' public API is absent of panicking.

kibwen4• 5 months ago

The vast majority of rust programs don’t need such validation.

The vast majority of Rust programs would benefit from such validation existing in the language, even if they never bother to explicitly leverage it themselves. For example, a non-panicking effect would be beneficial for both compilation times (don't bother pessimistically emitting unwinding glue for the enormous number of functions that don't need it, only to attempt to optimize it away later) and runtime performance (the guaranteed absence of the aforementioned glue reduces potential branch points and code size, which leads to better inlining and vectorization).

bionhoward• 5 months ago

gotta admit i groaned a bit at this because it would make rust more complicated, but on my 2nd read i realized:

- some things (compile time bounds checking tensor shapes) are hard / impossible to implement now; "pattern types" could be great for that

- however "no panic" is already handled by clippy, might not be much uplift for doing that at a type level.

my 2c: it's great to be excited and brainstorm, some of these ideas might be gold. conveying the benefit is key. it would be good to focus on stuff for which rust doesn't already have a workable solution. i like the pattern types, the rest would take convincing

shevy-java• 5 months ago

Rustee devs are strange. It feels as if they are on a mission. I don't fully understand it.

semiinfinitely• 5 months ago

the most exciting thing about rust is that AI agents are good at writing it because its so highly structured

Surac• 5 months ago

I do not write Rust. I have left c++ cause of the feature creep of the last years that made it even harder to read c++. Reading code is so important. Make language not unfriendly for readers and value the time people put into learning a language. I have seen many c++ programmers leaving cause they feel its an other language now

chadaustin• 5 months ago

I write Rust for embedded systems and both effects and linear types would be meaningful improvements. Effects especially: if you have multiple cores in a coherent memory domain AND you run with interrupts enabled, you have to deal with three types of mutex:

- data accessed by multiple cores and interrupt handlers must be modified under a spin lock and with interrupts disabled

- data accessed by multiple cores but not interrupt handlers only needs the spin lock

- data accessed by one core but maybe interrupt handlers only needs to pay for disabling interrupts

Depending on your core and how performance sensitive the code is, the costs of the above can vary significantly. It would be nice to encode these rules in the type system.

(Ordered types might be useful for “critical sections” — that is, areas where interrupts are disabled and the interrupt disablement guard absolutely must be dropped in order.)

jeffreygoesto• 5 months ago

Especially borrowing parts of objects reminds me of https://vale.dev

dzogchen• 5 months ago

The only thing Rust needs to have a chance to succeed is better C++ interoperability. Everything else is a nice to have.

ismailmaj• 5 months ago

Surprised with the push back of the comments, getting effects on Rust would be a dream.

Could even enable some stuff like passing loggers around not by parameters but by effect.

poppafuze• 5 months ago

"Because though we’re not doing too bad, we’re no Ada/SPARK yet" ... props to the king. A worthy aspiration. Classy.

theknarf2• 5 months ago

I'm surprised by the backlash in the comment section here, all of these things seems like the obvious next step for Rust. It seem people are scared of big words?

hu3• 5 months ago

It seem people are scared of big words?

Classic "skill issue" hubris by the language community.

kpcyrd• 5 months ago

I just want to be able to call Default::default() from within const {}

estebank2• 5 months ago

That's on the way. Already available in nightly for select types.

umanwizard5• 5 months ago

In formal terms, Rust’s type system is considered affine, which means that each value must be used at most once. And “use at most once” is exactly what’s needed to guarantee the absence of bugs like “use after free”.
But there are type systems which can provide even more guarantees. One step beyond “use at most once” is “use exactly once”. Types that provide that guarantee are called “linear” and in addition to guaranteeing the absence of “use after free” they can also guarantee the absence of memory leaks.

Does anyone know why these are called “affine” and “linear”, respectively? What’s the analogy, if any, to the use of those terms in math? (E.g. an affine transformation of vector spaces)

room271• 5 months ago

Rust needs to be careful that it doesn't invite the type-programming crowd in too much. Even if individual features are helpful, the cultural effect on the programming language in terms of the community (i.e. libraries and idioms) can really fragment and destroy a language. Scala, which I programmed in for many years, is a good example -- lots of great features but ultimately overwhelmed by typesafe abstractions that held theoretical appeal but hampered readability and fragmented the community. (Lack of backwards compatibility and poor tooling also hurt Scala no doubt about it, just as slow compile times hurt Rust.)

lsuresh2• 5 months ago

There are some solid ideas here and would definitely apply to the IVM engine we're building. I'm curious if some of these effects could play a role in faster rust compilation times (e.g. nopanic..)?

eviks• 5 months ago

Cool features, what are the chances that's going to happen in the next decade?

nmilo• 5 months ago

Rust is the wrong language for effects ironically because of its strict typing. They would probably decide that all effects have to be specified on every function or that any change in capabilities is a breaking change. Which is safest, but horrible for dev ex. Whereas Go most people would just be like “yeah, Hyrum’s law, sorry I broke your weird effect consumer, I don’t really care.”

xorvoid2• 5 months ago

I'm pretty conflicted on this comment section. A lot of people are expressing a lot of fear of C++ bloat. I get that.

I'm not sure what the right answer for Rust is, but I'm fairly convinced that these type system ideas are the future of programming languages.

Perhaps it can be added to rust in a reasonable and consistent way that doesn't ultimately feel like a kludgy language post-hoc bolt on. Time will tell. There is a serious risk to getting it wrong and making the language simply more complicated for no gain.

But, these ideas are really not obscure academic stuff. This is where programming language design is at. This moment is like talking about sum-types in the 2010s. These days that concept is normalized and expected in modern programming languages. But, that's a fairly recent development.

I suspect that Linear types, refinement types, etc will follow a similar trajectory. Whether new ideas like this can be reasonably added to existing languages in a good way is the age old question.

Hopefully Rust makes good choices on that road.

Levitating• 5 months ago

There is a serious risk to getting it wrong and making the language simply more complicated for no gain.

I think the Rust team/community is well-aware of this. Which is why Rust has such a well-defined RFC life-cycle.

At the other end, one of the biggest complaints about Rust is that many features seem eternally locked behind nightly feature gates.

xorvoid2• 5 months ago

I feel the same confliction about this organizational policy. It has been refreshing that they haven't just jammed half-baked ideas into stable like C++ has done for decades. But, yes, it's frustrating to bump into an issue and discover that a fix has been proposed and implemented but has never been moved to stable in 5-10 years. Some things feel like they're languishing in nightly forever.

I don't personally have a solution to propose to this problem. I generally appreciate their caution and long-term considering. It's refreshing coming from C++. I suppose one could argue that they've overcorrected in the other direction. Unclear.

Deeper than that, I think there's a philosophical dispute on whether languages should or shouldn't even evolve. There are people with C-stability type thinking that would argue that long-term stability is so important that we should stop making changes and etch things into stone. There is some merit to that (a lot of unhelpful churn in modern programming). But, failure to modernize is eventually death IMHO. I think C is slowly dying because of exactly this. It will take quite a while because it is critical computing infrastructure. But, few people remain that defend it's viability. The arguments that remain are of the form "we simply don't have a viable replacement yet".

Perhaps you can even take the view that this is the lifecycle of programming languages. They're not supposed to live forever. That could be a reasonable take. But then you really have to confront the problem of code migration from old languages to new languages. That is a very very hard unsolved problem (e.g. see: COBOL).

Language evolution is foundationally a hard problem. And I'm not unhappy with Rust's approach. I think no one has managed to find an ideal approach.

baroudi• 4 months ago

Introducing more colors (or effects) without a way to abstract over them will cause a lot of issues. It is already painful to work with async, one have to either accept a lot of code duplication or to perform some obscure black magic with the macro system.

Also, the language is already inelegant with each monad having its own syntactic sugar (result, option and async).

jk-pasha• 4 months ago

There’s one other way to look at it - in the age of vibe coding it makes sense to make the language more safe. Easier for the AI not to shoot itself in the foot.

But we’re gonna need better tools for reading this new denser code packed with gotchas. That’s for sure.

My “grand vision” for Rust

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