• 11 Posts
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Joined 4 months ago
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Cake day: February 26th, 2024

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  • Yeah, sorting is definitely a common use case, but note it also didn’t improve every sorting use case. Anyway, even if I’m a bit skeptical I trust the Rust team that they don’t take these decisions lightly.

    But the thing that lead to my original question was: if the compiler itself uses the std sorting internally, there’s also additional reason to hope that it might have transitive performance benefits. So even if compiling the Rust compiler with this PR was actually slower, compiling again with the resulting compiler could be faster since the resulting compiler benefits from faster sorting. So yeah, fingers crossed 🤞


  • Yeah, it was the first line of the linked PR:

    This PR replaces the sort implementations with tailor-made ones that strike a balance of run-time, compile-time and binary-size, yielding run-time and compile-time improvements.

    It was also repeated a few paragraphs later that the motivation for the changes was both runtime and compile time improvements. So a little bit bumped to hear the compile time impact wasn’t as good as the authors hoped apparently. I’m not even sure I fully endorse the tradeoff, because it seems the gains, while major, only affect very select use cases, while the regressions seem to affect everyone and hurt in an area that is already perceived as a pain point. But oh well, the total regression is still minor so I guess we’ll live with it.





  • For a little bit I thought this library might be a subtle joke, seeing the #define _SHITPRESS_H at the start. That combined with the compress() and decompress() not taking any arguments and not having a return value, I thought we were being played. Not to mention the library appears to be plain C rather than C++… surely the author should know the difference?

    Then I saw how the interface actually works:

    // interface for the library user, implement these in your program:
    unsigned int SPR_in(); // Return next byte from input or value > 255 on EOF.
    void SPR_out(unsigned char); // Output byte.
    

    This seems extremely poorly thought out. Calling into global functions for input and output means that your library will be a pain to use in any program that has to (de)compress anything more than a single input.







  • The other day I saw a link to Verus on here and it’s made me somewhat interested in the topic how Rust and formal verification can work together.

    It’s quite insightful to see how the borrow checker both required and ended up facilitating the ability to do more extensive formal verification on Rust code.

    Something like Verus (I haven’t looked into most of the other tools in this space yet, there seem to be many!) does appear poised to make verification quite approachable in low-level, self-contained Rust code already, and I’m curious to see how things evolve from there.

    It would be exceedingly cool if one day there’s a subset of libraries on crates.io that are fully verified (similar to how today there’s a subset that supports no-std development) and which are then usable to build upon in your own formally verified code.





  • I greatly fear refactoring in Rust. Making a single conceptual change can require a huge number of code changes in practice, especially if it’s a change to ownership.

    I think this is a fair criticism, but I think you and the poster you responded to are talking about different things. Usually when people use the term “fearless” in relation to Rust, it means the language provides a high level of confidence that what you’re delivering is free of mistakes. This certainly applies to refactoring too, where usually after you are done, and things compile again, you can be reasonably confident things work as before (assuming you didn’t make other changes the type system can’t catch for you).

    The kind of fear you are describing sounds more like a discouragement because of the amount of work ahead of you. That’s fair, because Rust does sometimes make things harder. I just think many Rust developers will disagree with you, not because you’re wrong, but because they may not feel the same type of discouragement, possibly because they’ve learned to appreciate the rewards more.


  • Agreed on all counts, except it being useless to think about :) It’s only useless if you dismiss philosophy as interesting altogether.

    But that kinda misses the point, right? Like, all that means is that the observation may have created the particle, not that the observation created reality, because reality is not all particles.

    I guess that depends on the point being made. You didn’t raise this argument, but I often see people arguing that the universe is deterministic and therefore we cannot have free will. But the quantum mechanical reality is probabilistic, which does leave room for things such as free will.

    I can agree with your view to say observation doesn’t create reality, but then it does still affect it by collapsing the wave function. It’s a meaningful distinction to make in a discussion about consciousness, since it leaves open the possibility that our consciousness is not merely an emergent property of complex interaction that has an illusion of free will, but that it may actually be an agent of free will.

    And yes, I fully recognise this enters into the philosophical realm and there is no science to support these claims. I’m merely arguing that science leaves open a path that enters that realm, and from there it is up to us to make sense of it.

    There is the philosophical adage “I think therefore I am”, which I do adhere to. I know I am, so I’ll consider as flawed any reasoning that says I’m not. Maybe that just makes me a particularly stubborn scientific curiosity, but I like to think I’m more than that :)


  • can you define physical for me?

    The distinction I tend to make is between physical using the classical definition of physics (where everything is made of particles basically) and the quantum mechanical physics which defies “physical” in the classical sense. So far we’ve only been able to scientifically witness quantum physics in small particles, but as you say, there’s no reason it can’t apply at a macro scale, just… we don’t know how to witness it, if possible.

    it doesn’t require an observer to collapse the wave function

    Or maybe it does? The explanation I have for us being unable to apply the experiments at a larger scale is that as we scale things up, it becomes harder and harder to avoid accidental observation that would taint the experiment. But that’s really no more than a hunch/gut feeling. I would have no idea how to prove that 😅


  • In fact, one of the great mysteries of physics right now is why only quantum objects have that property, and in order to figure that out we have to figure out what interaction “observation” actually is.

    This does not stroke with my understanding of quantum physics. As far as we know there is no clear distinction between “quantum objects” vs “non-quantum objects”. The double slit experiment has been reproduced with molecules as large as 114 atoms, and there seems no reason to believe that would be the upper limit: https://www.livescience.com/19268-quantum-double-slit-experiment-largest-molecules.html

    This proves that the wave is in fact real, because we can see the effects of it.

    The only part that’s proven is the interference pattern. So yes, we know it acts like a wave in that particular sense. But that’s not the same thing as saying it is a wave in the physical sense. A wave in the classic physical sense doesn’t collapse upon observation. I know it’s real in an abstract sense. I’m just questioning the physical nature of that reality.


  • Thanks, that seems a fair approach, although it doesn’t have me entirely convinced yet. Can you explain what the physical form of a wave function is? Because it’s not like a wave, such as waves in the sea. It’s really a wave function, an abstract representation of probabilities which in my understanding does not have any physical representation.

    You say the building does not start acting like a wave, and you’re right, that would be silly. But it does enter into a superposition where the building can be either collapsed or not. Like Schreudinger’s cat, which can be dead or alive, and will be in a superposition of both until observation happens again. And yes, the probabilities of this superposition are indeed expressed through the wave function, even though there is no physical wave.

    It’s true observation does not require consciousness. But until we know what does constitute observation, I believe consciousness provides a plausible explanation.