No solution, but I have a similar issue with the higher crate.

There the /prelude/src/lib.rs file lets rust-analyzer lose its mind and allocate gigabytes upon gigabytes of memory, even though the file compiles just fine and nearly instantaneous…

I think this has something to do with recursive macros. Doesn’t iced also have such? I have faint memories of a column! macro?

• cargo install is for installing rust programs for your user, not for adding dependencies to your Rust project. Many cargo subcommands can be installed this way, for instance cargo bloat.
• The file you are talking about is called Cargo.toml, because it is the file you need to write in order to configure cargo for your Rust project. TOML is the name of the file format. For details, please see the introductory chapter to Cargo in the Rust book.
• Cargo recently got a new subcommand called cargo add, which allows to add dependencies directly on the command line. However, all it does is to add/edit/remove the respective lines in Cargo.toml. (Personal opinion: I have found it way easier to just edit the file directly than to learn yet another command…)

That said: You still need to edit the Cargo.toml file, even if you solely use cargo add to manage your dependencies. That’s because that file contains a lot more information about your project than just the dependencies. For instance the current version, the feature-flags, your name, a link to the public repo,…

I haven’t done much Rust coding this year yet, mainly because I am trying to learn Lean4 and spent the last couple of months writing a (partially) formally validated (but not very fast) Binary Heap in Lean4.

However, a few days ago I had an inspiration at night, that brought me back to my Rust spare time project: The visual novel engine I had started last year.

For now I only did a relatively small change, but it’s one that will save me a lot of time (and nerves) later on. I am using a Free Monad based embedded Domain Specific Language for writing the game logic. The change now was to wrap that Free Monad in a State Monad Transformer, which I use to store the game state in.

This idea seems to be working surprisingly well, and that has given me enough motivation to return to this project and to keep developing it further for now.

Long and boring explanation with way too much detail:

Sorry for going on a tangent, but there is a Rust-specific detail that makes this cool beyond the usual advantages of using a State Monad Transformer, and I cannot stop myself from sharing.

For composing a large Free Monad, do-notation is more or less a must-have. However, do-notation in Rust only works well with types that implement Copy. If you want to use any other type in do-notation, you can only access variables of it in the following two lines. An attempt to access the data later will lead to an ownership problem (explained here). I have tried to overcome this by adding additional syntax to do-notation, but that is a crutch at best.

So, this is where the State Monad Transformer comes in. It side-steps this problem by moving the state out of the do-notation block into the Free Monad’s Pure-nodes. That way it is readily available via the State Monad Transformer’s get()/put() functions, and the “use within two lines” limitation is not a big issue any more, as one can always get the value on one line, do something with it in the next line, and write the result back on the second line.

I would be very surprised if they wouldn’t fix all 50 filesystems.

In all projects I have worked on (which does not include the Linux kernel) submitting a merge request with changes that don’t compile is an absolute no-go. What happens there is, that the CI pipeline runs, fails, and instead of a code review the person submitting the MR gets a note that their CI run failed, and they should fix it before re-opening the MR.

That’s a very good point. I hadn’t considered potential lack of domain knowledge at all. In that case Rust might even help, because it’s easier to write interfaces that can’t be used wrong - so that even someone without the needed domain knowledge might be able to fix compile issues without breakage.

Behind all the negative tone there is a valid concern though.

If you don’t know Rust, and you want to change internal interfaces on the C side, then you have a problem. If you only change the C code, the Rust code will no longer build.

This now brings an interesting challenge to maintainers: How should they handle such merge requests? Should they accept breakage of the Rust code? If yes, who is then responsible for fixing it?

I personally would just decline such merge requests, but I can see how this might be perceived as a barrier - quite a big barrier if you add the learning cliff of Rust.

Points that I would gladly agree upon - but it seems the Wikipedia authors don’t.

I am not knowledgeable enough to draw a definite line what counts as functional and what doesn’t - so I chose to go with whatever Wikipedia says… Even though I dislike it.

I know, from a mathematics standpoint it does not make sense, but from how the term is used nowadays in programming it does: Those languages allow to compose functions, pass functions as parameters, return functions, etc.

Truth has been spoken.

Except that Kotlin is functional (just like Rust, C++, Visual Basic, JavaScript,…). It is, however, not Pure Functional (like Haskell or Lean4 would be - if you haven’t checked out Lean4, I can recommend it, great fun).

(Sauce: https://en.wikipedia.org/wiki/List_of_programming_languages_by_type#Functional_languages)

And for it to be a worthwhile saving in low memory or storage situations, further constraints need to be met too. For instance, you would need to compile your own standard library, or go fully no-std…

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I am still in the process of customizing my desktop on my new MNT Reform laptop. This includes some work on my status bar tool. I just fixed decibel scaling for the ALSA volume plugin yesterday: https://github.com/soulsource/swaystatus/tree/feature/alsa

I am planning to merge the ALSA plugin to the main branch this week.

Next thing to add is a battery display. Probably using the udev crate, though I am tempted to just use sysfs instead.

Visual Studio Code with rust-analyzer has all the features I would expect from an IDE. I mean, rust-analyzer works together with cargo, so refactoring over file boundaries is not an issue. Visual Studio Code has built-in support for debugging and source control…

That said, I am currently trying to change my workflow to use vim instead of Visual Studio Code, due to my laptop’s small screen size. Rust-analyzer works great in vim too, but I still need to tweak a few things, like how warnings from cargo check are being displayed…

I’m mostly using Rust for a spare time Visual Novel Engine (and Visual Novel) project.

I picked Rust, because I wanted to do something productive with my higher-free-macro crate (which is a tech-demo, but hey, if I have written it, I can just as well use it for something). If you want to get an idea how scripting the VNs in that engine will work, check out the “text adventure” example in higher-free-macro. However, Rust is definitely not an ideal choice for this project. Since performance usually isn’t a concern for visual novels, a higher-level, pure functional language like Haskell or Lean4 would probably have been a better option.

Apart from that I’m using it for many smaller things. For instance I’ve written a small tool for my status bar, swaystatus. (I was not aware that i3status-rust exists when I started working on it, and now I am already committed.) Here I chose Rust mainly because I wanted to learn about Foreign Function Interface in Rust. While I didn’t upload the sources to github until recently, I mostly had been working on this tool several years ago, when I still was a Rust newbie. However, I got back to this project some weeks ago, when I realized that I would like to have an ALSA volume display, which is now in a WIP state on a separte branch.

I’m also using Rust for some out-of-tree prototypes at work. In this case the main reason for choosing Rust is development speed. I’m using Iced.rs to build those prototype GUIs, and Iced is an amazing toolkit. Making a prototype with it is shockingly fast. If I were to do something similar with basically any other GUI toolkit, it would take me significantly longer.

And last, but not least: I’ve published a free app for SailfishOS which is compatible with passwordmaker.org: Passfish, and its underlying library, passwordmaker-rs. Here I chose Rust, because it’s way less error prone than C++ (and let’s better not talk about QML JavaScript). Also, I wanted to show that using Rust for SailfishOS app development is viable, and that it’s actually a quite pleasant experience. (If you want to try passfish, builds are available via the official SailfishOS store, or on OpenRepos).

I second the recommendation to start with The Book. It contains all the necessary information, especially in the chapter about ownership.

I wouldn’t call Monads a “language feature” of Rust.

There are some types in the standard library that have Monad properties (Option, Result, Vec,…), but there is no Monad trait that would allow to be generic over them.

There have been attempts to introduce such a trait, the most well known probably being the higher crate. However, even with that crate, it’s not easy to work with Monads.

For instance, in the stable tool-chain, it’s currently (to my knowledge) not possible to express a Free Monad without using macros. If you care for the details, I’ve written a blog post about my Adventures with Free Monads and higher. With the Nightly toolchain it is possible to write a generic Free Monad, by the way, thanks to non-lifetime-binders.

Other Monads, like State, Reader and Writer, are also challenging to implement in Rust. I did get them to work, however I failed to implement Applicative for them, so, while they are mathematically Monads, they do not have higher’s Monad trait. Here a possible future improvement of non-lifetime-binders could help. Again, a blog post: Writer and State Monad in Rust, based on higher.

Oh, and last, but not least, do-notation in Rust is a bit inconvenient, because of lifetime rules and lambda captures. For instance, using non-copy types is messy. I’ve added explicit clone support to higher, but that’s a crutch, and overly verbose.

There is also the y-combinator thread that discusses async as implemented in Rust compared to using Monads to represent async computations: https://news.ycombinator.com/item?id=17536441

The arguments that withoutboats presented in that thread convinced me that Rust’s async is the better of these alternatives for a language like Rust.

Another thing that helped to convince me of that is that I tried playing around with Free Monads and the Writer and State Monad in Rust, and found them to be very un-ergonomic. Rust is very explicit about heap allocations, and when using basically any Monad that’s more complex than Option/Result I found myself typing Rc::new() way more often than I would have liked… If you add do-notation to the mix, things get even more verbose (aka: annoying): https://github.com/bodil/higher/issues/6

So, yeah. Rust async isn’t perfect, but it’s probably better to have it than not.

We are in a better situation regarding the addition of new languages. Most of our devs (don’t know the exact count, 40-50 I guess) are dissatisfied with C++ in one way or another. Our company started out with Unity (which uses .Net), so most of our senior devs have experience with other languages too, and those who don’t are generally young people who haven’t had time to get stubborn yet 😜.

Our technical director pushes towards functional programming pretty strongly, and he gave most of us the opportunity to participate in a course by FP Complete, which was a bit about Haskell, but mostly about Rust. So, most of our coders have at least seen Rust. Some liked it enough to do spare time projects in it, and as far as I can tell there is no strong dislike towards the language from anyone in our team.

However, there is no consensus yet amongst seniors which language besides C++ we should introduce. Our tech director leans towards Rust for business reasons (-> the argument is that many devs like Rust, so finding Rust devs should be easy). Some, though they dislike C++, would rather keep it exclusively, as they doubt the benefits of other languages would outweigh the overhead (training, writing FFI bindings). Then there are those (including me) who would go directly for a pure functional language…

And last, but not least, there is the biggest reason why we haven’t introduced any languages besides C++ yet: Time. We would need time to experiment with integrating languages into our tooling, and we simply are too busy at the moment to do that…

The “it’s hard” claim is also a bit of a misconception imho. Rust for sure has a high entry barrier, but it isn’t particularly difficult, at least in comparison with C++, which I’d consider its biggest competitor. While it’s easy to start working with C++, it’s a horribly complex language with hard to use features, lots of weird edge cases, and tons of missing pieces, that one has little chance of ever learning properly, because it’s just so much to keep in mind at all times… Oh, and don’t get me started on how error prone memory management is without a Borrow Checker…

Sorry for the rant, back on topic: I agree that it’s not the right tool for many domains. That’s what I was thinking about when I wrote that people might misunderstand what niche it tries to fill. If one needs a low level language that is very explicit about performance costs, and offers memory safety and (some) abstraction at zero runtime cost, then Rust is definitely worth a look. If performance is not a key concern, then higher level languages might be a better choice, because one can build things faster, and focus more on the problem at hand instead of low-level details.

We are at work in a similar situation, as we would like to add another programming language besides C++ to our projects, and Rust is currently the top candidate. However, one of our goals is to use abstractions that are common in functional programming, and that’s where I think Rust is a suboptimal choice. I’ve been playing around with such abstractions in Rust recently (I’ve written blog posts about Free Monads and Reader/State Monads in Rust), and my conclusion is that Rust isn’t the right tool if one wants to use those. (Or, rather, those abstractions are not suited for the domain of systems programming.)

We are using Unreal Engine, so C++ is the obvious choice for performance critical code. Rust would then fill the same niche, and while it obviously would be much more convenient to use than C++, we would still need to train people, and set up FFI bindings. If we, however, are already willing to do that, we could also go all the way and introduce a higher level pure functional language. That way we would actually get a tool that covers a different domain and is suitable for abstractions coming from functional programming. We could then choose, based on a system’s requirements, if we need to focus on performance (-> C++), or if we can trade a bit of performance for much easier to write/maintain code (-> whatever high level functional language we pick).

That’s why, as it stands now, I also won’t push towards the adoption of Rust at work.

Controversial opinion: There are only 2 kinds of people that think Rust will not become a widely used language:

• Those who don’t bother to learn it, and only argue about it without any hands-on experience, and
• those who don’t understand which niche Rust tries to fill.

For me it was funny, btw. I started out as basically a Rust fanboy, back when the “First Edition of The Rust Book” was still just called “The Book”…

Then I learned a bit of Haskell, and was immediately disappointed that Rust doesn’t offer the same convenience when it comes to working with Traits (cough Higher Kinded Types cough). So, while I never considered myself part of the first group, I definitely was part of the second for some time.

However, the more I’ve been trying to abuse Rust for stuff that would be better done in a higher level language (like Haskell), the better I understood why Rust doesn’t offer those abstractions: They often can’t be zero-cost, and using them in a language that tries to be very explicit about performance costs becomes very verbose… In other words, I learned the hard way what “systems programming” means in the case of Rust, and which languages it competes with, and which it doesn’t.