The topic of the Rust experiment was just discussed at the annual Maintainers Summit. The consensus among the assembled developers is that Rust in the kernel is no longer experimental — it is now a core part of the kernel and is here to stay. So the “experimental” tag will be coming off. Congratulations are in order for all of the Rust for Linux team.
Thanks, I might take a look at it just for fun. 😀
Enjoy! I don’t know what you used to seriously program on but I am willing to bet that the ownership paradigm that it enforces is going to feel at least moderately new to you, unless you forced yourself to code that way anyways.
Plus, as long as you’re doing silly little home projects, the compiler errors are the absolute best I’ve ever seen. Literally just learn basic syntax, try it out, and when it does not compile, the compiler not only tells you why but also what it thinks you’re trying to do and how to fix.
Absolute gem of a learning tool.
Thinking about ownership is the right way e.g. for C++ as well, so if one has coded professionally in larger systems, it should not be too alien.
One still needs to learn life time annotations. So, assuming that you know, for example, C++, it is an a bit larger hurdle than picking up Java or Go, but it is worth the time.
In many aspects, Rust is far more productive and also more beginner-friendly than C++:
I could go on… but I need to do other stuff
What’s wrong with implementation inheritance? Don’t you want that?
Generally no. As soon as a class hierarchy becomes moderately complex, implementation inheritance makes code very hard to maintain, because you need to read the whole stack of classes to see what a single change will actually do.
Rust has another system, traits and trait implementations.
The consensus seems to be that implementation inheritance leads to code that is difficult to understand and difficult to reuse. Its perhaps the main reason C++ is banned from the kernel.
Thanks for the detailed answer. Preaching to the choir.
The existence of the concept of ownership in languages like C++ is why I threw “moderately” in there. I agree depending on what you take that to mean, it may or may not do some heavy lifting.
For the rest, I’d divide it into hard facts (compiler messages are absolutely undeniable, in any circumstance) and things that can definitely be true depending on your personal use cases. I’m with you on this: for the vast vast majority of tasks commonly understood as software engineering, memory safety is a concern, and a lot, if not all, of your points, are valid.
I must humbly insist that it does not fit my needs, in the sense that memory safety is of no concern to me, and that the restrictions that a compiler-enforced approach imposes make me less productive, and, subjectively, also less enjoyable because causing more friction.
That being said, you may also not consider what I’m currently doing to be software engineering, and that’s totally fine. Then we’d agree entirely.
EDIT: also, there are very few languages less productive and beginner-friendly than C++ in my opinion. The proverbial bar is in hell. But you are talking to an unreasonable C++ hater.
I am a professional C++ developer with 20 years of experience and have worked in about eight other languages professionally, while learning and using a dozen more in hobby projects.
I agree with you here. The only areas where specifics are worse are package management in Python, and maintainability of large SIMULINK models.
That’s the sort of indictment of C++ I like to hear. It’s not just me then. I sometimes feel like I’m taking crazy pills with some colleagues who are super enthusiastic about it still.
But again, I’m stupid, I know I’m stupid, and C++ has way too many features and convoluted behaviours which are hard for me to remember and reason about. It often feels like it makes me think more about the language problems than the actual problem I’m supposed to work on. It may say more about me than the language, but I do feel validated with comments like this.
Absolutely, I am more used to program closer to the iron mostly C. My favorite was 68000 Assembly, python is nice, but I prefer compiled languages for efficiency. Although that efficiency isn’t relevant for basic tasks anymore.
The compiler error messages sound extremely cool. 👍
Ah, a fellow C coder. Never did do assembly with chips older than x86_64 basically. The only old school stuff I touched was writing an interpreter for the CHIP-8. I tried writing some CHIP-8 too, but coming from more recent paradigms, it seemed quite unwieldy to me.
I like python for quick and dirty stuff, I don’t like python for being interpreted and it being not obvious what happens under the hood, memory wise, at a glance.
Seeing as you do C I’ll say this. The one thing I really did not enjoy, subjectively, with Rust, is that writing “C-style loops” comes with a performance penalty because there are bound checks happening, so the idiomatic version of a loop in Rust usually involves iterators and function composition.
I am stupid. C-loops are easy for me to understand. More sophisticated stuff is hard for my little brain. I’d rather be trusted with my memory access, and be reminded of my stupidity when comes the inevitable segfault. Keeps you humble.
To me it feels like it does things I didn’t ask it to. So I’m not 100% in control 😋
What? You need to make a function to make a loop? That can’t be right???
Absolutely, the way C loops work is perfect. I’m not so fond of the syntax, but at least it’s logical in how it works.
Ah no, there is a misunderstanding. You can write C-loops, of course, they just could involve more work under the hood because in order to enforce memory safety, there needs to be some form of bounds checking that does not happen in C. Caveat: I don’t know whether that’s always true, and what the subtleties are. Maybe I’m wrong about that even, but what is true is that what I am about to say, you will encounter in Rust codebases.
By function composition I meant in the mathematical sense. So, this example explains the gist of it. You may need to throw in a lambda function in there to actually do the job, yeah. I don’t know what the compiler actually reduces that to though.
It’s just the more functional approach that you can also see with Haskell for example. I find it harder to parse, but that may be lack of training rather than intrinsic difficult.
EDIT: pasted the wrong link to something totally irrelevant, fixed now
OK thanks for clarifying. 👍
If you don’t like the functional syntax you can usually use for each loops to the same effect.
There is one more little secret that not everyone knows:
You do not need lifetime annotations and full borrow checking if you do not care to press out the last drop of performance out of the CPU, or if you just draft experimental code.
In fact, you can very much program in a style that is similar to python:
This makes your code less efficient, yes. But, it avoids to deal with the borrow checker before you really need it, because the copied values get an own life time. It will still be much faster than Python.
This approach would not work for heavily concurrent, multi-threaded code. But not everyone needs Rust for that. There are other quality-of-life factors which make Rust interesting to use.
… and of course it can’t beat Python for ease of use. But it is in a good place between Python and C++. A bit more difficult than Java, yes. But when you need to call into such code from Python, it is far easier than Java.
IIRC you can speed up such checks by putting an assertion in front that checks for the largest index - this will make repeated checks for smaller indices unnecessary. Also, bound checks are often not even visible on modern CPUs because speculative execution, branch prediction, and out-of-order execution. The CPU just assumes that the checks will succeed, and works on the next step.
I had no idea about the assertion! Thanks.
Yes, this is plain wrong or often unimportant on modern architecture, you’re right. I, certainly mistakenly, thought this was one of the reasons for the idiomatic version involving function composition, which is the thing I, subjectively, don’t enjoy as much.
I stand corrected.
The function composition style comes from functional programming and Rust’s OCaml heritage. It can make it easier to reason about invriants and possible sets of values of the result of a computation step.
Rust transforms these to the same or a close equivalent of hand-written loops.
Similar methods are used in specialized, high-performance C++ libraries such as blitz++ and Eigen. But if you mess up bounds, you will get UB with them.