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I’m relatively qualified. Studied physics all through college and spent a couple years working in quantum computing. I’ll chime in here because Schrodinger’s cat jokes are a pet peeve.
You are correct that, as far as we understand, it is literally impossible. There has been a competing theory for decades, but I’m not really up on the specifics https://en.wikipedia.org/wiki/De_Broglie–Bohm_theory. The reason it is generally rejected is that it appears to violate relativity.
Anyway… the cat thought experiment is such a fun thought experiment to me because it specifically makes us think about a very practical issue with respect to quantum computing: decoherence. If you take his thought experiment to an extreme, it actually should be theoretically possible to create a state in which a macroscopic object (the cat) and a quantum object (the radioactive source) are indeed entangled. But that is absurd according to everything we’ve ever seen. So what’s up? The missing concept here is decoherence – while this state may theoretically exist, it’d decohere on timescales so small we can’t even imagine. The fun connection here is that decoherence is the exact thing we’re trying to fight in quantum computing. Essentially we’re trying to make this thought experiment a reality for a much less complex system.
Some more on decoherence: https://en.wikipedia.org/wiki/Quantum_decoherence
I agree and think that should be helpful, but I hesitate to say how much easier that actually makes writing sound unsafe code. I’d think most experienced C developers also implicitly know when they’re doing unsafe things, with or without an unsafe block in the language – although I think the explicit unsafe should likely help code reviewers and tired developers.
It is possible to write highly unsafe code in Rust while each individual unsafe block appears sound. As a simple example: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=6a1428d9cae5b9343b464709573648b4 [1] Run that on Debug and Release builds. Notice the output is different? Don’t take that example as some sort of difficult case, you wouldn’t write this code, but the concepts in it are a bit worrisome. That code is a silly example, but each individual unsafe block appears sound when trying to reason only within the block. There is unsafe behavior happening outside of the unsafe blocks (the do_some_things function should raise eyebrows), and the function we ultimately end up in has no idea something unsafe has happened.
Unsafe code in Rust is not easy, and to some extent it breaks abstractions (maybe pointers in general break abstractions to some extent?). noaliases in that playground code rightly assumes you can’t have a and &mut ref to the same thing, that’s undefined behavior in Rust. Yet to understand the cause of that bug you have to look at all function calls on the way, just as you would have to in C, and one of the biggest issues in the code exists outside of an unsafe block.
[1]: If you don’t want to click that link or it breaks, here is the code:
fn uhoh() {
let val = 9;
let val_ptr: *const usize = &val;
do_some_things(val_ptr);
println!("{}", val);
}
fn do_some_things(val: *const usize) {
let valref = unsafe { val.as_ref().unwrap() };
let mut_ptr: *mut usize = val as *mut usize;
do_some_other_things(mut_ptr, valref);
}
fn do_some_other_things(val: *mut usize, normalref: &usize) {
let mutref = unsafe { val.as_mut().unwrap() };
noaliases(normalref, mutref);
}
fn noaliases(input: &usize, output: &mut usize) {
if *input < 10 {
*output = 15;
}
if *input > 10 {
*output = 5;
}
}
fn main() {
uhoh();
}
The important point there is that they don’t care imo. It’s not even worth the effort to try.
You can likely come up with something “good enough” though yea. Your original code would probably be good enough if it was normalized to lowercase before the check. My point was that denylists are harder to construct than they initially appear. Especially in the LLM case.
This is not true at all. https://en.wikipedia.org/wiki/Post-quantum_cryptography good place to start if you’re genuinely interested. Most password managers that are worth while will be using symmetric cryptography which just requires longer key lengths to survive in the quantum age. AES256 should be fine for the foreseeable future.
Redox also takes some inspiration from Plan9 and https://doc.redox-os.org/book/ch05-00-schemes-resources.html is interesting. Also reading https://drewdevault.com/2022/11/12/In-praise-of-Plan-9.html made me a bit more interested in things trying to be more Plan9-like than Unix-like.
This doesn’t seem to be a Rust problem, but a modern development trend appearing in a Rust tool shipped with Cargo. The issue appears to be the way things are versioned and (reading between the lines maybe?) vendoring and/or lockfiles. Lockfiles exist in a lot of modern languages and package managers: Go has go.sum, Rust has Cargo which has Cargo.lock, Python has pip which gives a few different ways to pin versions, JavaScript has npm and yarn with lock files. I’m sure there are tons of others. I’m actually surprised this doesn’t happen all the time with newer projects. Maybe it does actually and this instance just gains traction because people get to say “look Rust bad Debian doesn’t like it”.
This seems like a big issue if you want your code to be packaged by Debian, and it doesn’t seem easy to resolve if you also want to use the modern packaging tools. I’m not actually sure how they resolve this? There are real benefits to pinning versions, but there are also real benefits to Debian’s model (of controlling all the dependencies themselves, to some extent Debian is a lockfile implemented on the OS level). Seems like a tough problem and seems like it’ll end up with a lot of newer tools just not being available in Debian (by that I mean just not packaged by Debian, they’ll likely all run fine on Debian).
They’re being downvoted because it’s a silly comment that is basically unrelated and also extremely unhelpful. Everyone can agree that C has footguns and isn’t memory safe, but writing a kernel isn’t memory safe. A kernel written in Rust will have tons of unsafe, just look at Redox: https://github.com/search?q=repo%3Aredox-os%2Fkernel unsafe&type=code That doesn’t mean it isn’t safer, even in kernel space, but the issues with introducing Rust into the kernel, which is already written in C and a massive project, are more nuanced than “C bad”. The religious “C bad” and “C good” arguments are kinda exactly the issue on display in the OP.
I say this as someone who writes mostly Rust instead of C and is in favor of Rust in the kernel.
No intention of validating that behavior, it’s uncalled for and childish, but I think there is another bit of “nontechnical nonsense” on the opposite side of this silly religious war: the RIIR crowd. Longstanding C projects (sometimes even projects written in dynamic languages…?) get people that know very little about the project, or at least have never contributed, asking for it to be rewritten or refactored in Rust, and that’s likely just as tiring as the defensive C people when you want to include Rust in the kernel.
People need to chill out on both sides of this weird religious war. A programming language is just a tool: its merits in a given situation should be discussed logically.