4 ms·

I have written around 30k+ lines of rust by now, and I have to agree with OP. I have encountered many situations where perfectly reasonable, zero copy, memory m

I have written around 30k+ lines of rust by now, and I have to agree with OP. I have encountered many situations where perfectly reasonable, zero copy, memory management that would be completely normal, fast and safe in C, it basically impossible to replicate in Rust (or at least I am not clever enough to figure it out). Are there other ways to structure the data that work in Rust? Yes, of course. Do I like them compared to the C one? No, not at all. Do I think that the additional memory safety that comes from Rust is worth it? In some use cases, yes

insanitybit 4y ago
If you were clever enough to write it safely in C I can guarantee you'd be clever enough to write it in Rust.
- francasso 4y ago
  Oh boy, that is so not true. Anything where the boundaries of the lifetimes are easily determined at runtime but unknown at compile time is extremely easy to model safely in C, and a nightmare in Rust. At least if you want the same level of performance and a similar modeling of the data
  - nu11ptr 4y ago
    Rust lifetimes are just the lifetimes of the memory, exactly the same as C. The only difference is you simply need to (sometimes) tell Rust where the memory for a reference comes from explicitly, where as in C you don't (but in C if you get it wrong your program will segfault, unlike Rust, or worse it might not...sometimes).
    - skribanto 4y ago
      Well yes, lifetimes also exist in C, but it is only in Rust that they are compiler checked
    - celeritascelery 4y ago
      > Rust lifetimes are just the lifetimes of the memory, exactly the same as C. Rust lifetimes are only the lifetimes of the memory that are provable by the type system. There are many valid lifetimes that are not provable. For example lifetimes that change at runtime, and self referencing lifetimes, or cyclic lifetimes. Newer versions of the borrow checker enable it to prove more lifetimes correct, but it will never be able to express all valid lifetimes of the actual memory. This means some patterns the are completely valid cannot be expressed in safe Rust due to the limitations of the type system, but can be expressed in C.
      - insanitybit 4y ago
        And you can use unsafe.
  - insanitybit 4y ago
    > Anything where the boundaries of the lifetimes are easily determined at runtime but unknown at compile time is extremely easy to model safely in C, I don't even know how to respond to this seriously. I guess just imagine me pointing to every blatant instance of this not being true.
    - francasso 4y ago
      In my experience, the vast majority of examples where that fails is because of two reasons: project evolution that doesn't spend time re-evaluting memory managemnt together with the new requirements on the data, or inexperienced C coders. So that goes to my last point in my original post, yes as an industry there are use cases where rust is better because of the provably safe memory management (let's forget unsafe for the moment). But as a language you _can_ safely model those situations in C esily. The problem is that the solution is not robust to change. If you don't agree with that it will be me who doesn't know how to take what you say seriously
    - mumblemumble 4y ago
      With all due respect to Michael Palin, "this isn't an argument ... it's just contradiction." Perhaps, for the benefit of those of us observing if nothing else, it might be beneficial to identify some concrete examples to discuss before proceeding.
      - insanitybit 4y ago
        I dislike when a discussion turns into "I have to teach you the basics now". I'm just not willing to engage in that most of the time with strangers on the internet because they usually don't want to be taught, they want to be right. Explaining that you can express complex dynamic lifetimes in Rust using 'unsafe' and module-level safety is a waste of my time because it's empirically true.
        mumblemumble 4y ago
        But you are engaging with strangers on the internet. You're just not doing it in a way that's particularly edifying. Indirectly insulting me and others doesn't help your case on that front. Let me turn it back on you. By refusing to educate people on what you think they got wrong, you come across looking like just what you're worried about: someone who just wants to be right. If your goal is to defend Rust, I would suggest you either teach for yourself, or share links to others teaching the thing you want to communicate but don't want to type out, or, if neither of those, then to simply keep your peace and let someone else do the responding. Speaking for myself as an on-and-off Rust learner, I've got to say that the single biggest frustration I've experienced with learning the language is wading through all the low effort gainsaying in order to find the nuggets of digestible, practical advice about how to effectively use the language for non-toy problems. It's not that I can't do so, per se. It's just that it's really hard, and perhaps even counterproductive, to work up the motivation to wade through all the snark and invective when my original purpose was to try and unwind at the end of the day.
  - aew4ytasghe5 4y ago
    Um, lifetimes are not a made up concept of rust to be in your way. It helps you understand issues that would be real and undetected in your C app. Your C app would work by happy accident and you would not notice until later when data is corrupted in another part of your program. This is the rest of us wanted to leave C/C++.
nu11ptr 4y ago
I have written about 50K LoC of Rust, so fairly similar. I will agree that I have had occasional "lost days" with some very complex spots of code that would not have been a problem in a GC language. That said, I feel like I've made up for that at least 1.5-2x by my productivity and lack of bugs in other sections. That said, I can understand how it may not be for everyone. I love it, but there are some data structures you just have to code differently, and until you spend time thinking about how to do that, it would seem like wasted time you wouldn't get back. My personality may also be a fit: I'm very much a measure twice, cut once kind of person. I tend write my algorithms in pseudo code and sketch my data structures on paper before I touch the keyboard, so even in my "get it done" language I don't immediately just start coding always.
- deleted 4y ago
  [deleted]
root_axis 4y ago
> I have encountered many situations where perfectly reasonable, zero copy, memory management that would be completely normal, fast and safe in C So you think. It doesn't matter how smart you think you are, statistically speaking you're not smarter than a compiler.
- francasso 4y ago
  I think you are overestimating the expressive power of lifetime annotations in rust, and how smart the borrow checker is
  - estebank 4y ago
    Anything you can express in C, you can in Rust. When it comes to pointer tricks you might have to use unsafe, but that is part of the language.
    - platinumrad 4y ago
      If only 50% of the community didn't think it was their job to scream at complete strangers for using that part of the language.
      - nu11ptr 4y ago
        Agreed (unfortunately). There is too much of an obsession in avoiding unsafe at all costs in my opinion. When you consider all C/C++ is effectively written in an unsafe block then it seems a bit ludicrous to assume you would never ever use unsafe in tight, performant code.
easterncalculus 4y ago
Seeing some of the hassles with creating basic stuff like a linked list is part of the reason I have yet to use it seriously. I think I will eventually, but I certainly won't act like it doesn't come with a cost or that it always pays off.

insanitybit 4y ago

If you were clever enough to write it safely in C I can guarantee you'd be clever enough to write it in Rust.

francasso 4y ago
Oh boy, that is so not true. Anything where the boundaries of the lifetimes are easily determined at runtime but unknown at compile time is extremely easy to model safely in C, and a nightmare in Rust. At least if you want the same level of performance and a similar modeling of the data
- nu11ptr 4y ago
  Rust lifetimes are just the lifetimes of the memory, exactly the same as C. The only difference is you simply need to (sometimes) tell Rust where the memory for a reference comes from explicitly, where as in C you don't (but in C if you get it wrong your program will segfault, unlike Rust, or worse it might not...sometimes).
  - skribanto 4y ago
    Well yes, lifetimes also exist in C, but it is only in Rust that they are compiler checked
  - celeritascelery 4y ago
    > Rust lifetimes are just the lifetimes of the memory, exactly the same as C. Rust lifetimes are only the lifetimes of the memory that are provable by the type system. There are many valid lifetimes that are not provable. For example lifetimes that change at runtime, and self referencing lifetimes, or cyclic lifetimes. Newer versions of the borrow checker enable it to prove more lifetimes correct, but it will never be able to express all valid lifetimes of the actual memory. This means some patterns the are completely valid cannot be expressed in safe Rust due to the limitations of the type system, but can be expressed in C.
    - insanitybit 4y ago
      And you can use unsafe.
- insanitybit 4y ago
  > Anything where the boundaries of the lifetimes are easily determined at runtime but unknown at compile time is extremely easy to model safely in C, I don't even know how to respond to this seriously. I guess just imagine me pointing to every blatant instance of this not being true.
  - francasso 4y ago
    In my experience, the vast majority of examples where that fails is because of two reasons: project evolution that doesn't spend time re-evaluting memory managemnt together with the new requirements on the data, or inexperienced C coders. So that goes to my last point in my original post, yes as an industry there are use cases where rust is better because of the provably safe memory management (let's forget unsafe for the moment). But as a language you _can_ safely model those situations in C esily. The problem is that the solution is not robust to change. If you don't agree with that it will be me who doesn't know how to take what you say seriously
  - mumblemumble 4y ago
    With all due respect to Michael Palin, "this isn't an argument ... it's just contradiction." Perhaps, for the benefit of those of us observing if nothing else, it might be beneficial to identify some concrete examples to discuss before proceeding.
    - insanitybit 4y ago
      I dislike when a discussion turns into "I have to teach you the basics now". I'm just not willing to engage in that most of the time with strangers on the internet because they usually don't want to be taught, they want to be right. Explaining that you can express complex dynamic lifetimes in Rust using 'unsafe' and module-level safety is a waste of my time because it's empirically true.
      - mumblemumble 4y ago
        But you are engaging with strangers on the internet. You're just not doing it in a way that's particularly edifying. Indirectly insulting me and others doesn't help your case on that front. Let me turn it back on you. By refusing to educate people on what you think they got wrong, you come across looking like just what you're worried about: someone who just wants to be right. If your goal is to defend Rust, I would suggest you either teach for yourself, or share links to others teaching the thing you want to communicate but don't want to type out, or, if neither of those, then to simply keep your peace and let someone else do the responding. Speaking for myself as an on-and-off Rust learner, I've got to say that the single biggest frustration I've experienced with learning the language is wading through all the low effort gainsaying in order to find the nuggets of digestible, practical advice about how to effectively use the language for non-toy problems. It's not that I can't do so, per se. It's just that it's really hard, and perhaps even counterproductive, to work up the motivation to wade through all the snark and invective when my original purpose was to try and unwind at the end of the day.
- aew4ytasghe5 4y ago
  Um, lifetimes are not a made up concept of rust to be in your way. It helps you understand issues that would be real and undetected in your C app. Your C app would work by happy accident and you would not notice until later when data is corrupted in another part of your program. This is the rest of us wanted to leave C/C++.

nu11ptr 4y ago

I have written about 50K LoC of Rust, so fairly similar. I will agree that I have had occasional "lost days" with some very complex spots of code that would not have been a problem in a GC language. That said, I feel like I've made up for that at least 1.5-2x by my productivity and lack of bugs in other sections. That said, I can understand how it may not be for everyone. I love it, but there are some data structures you just have to code differently, and until you spend time thinking about how to do that, it would seem like wasted time you wouldn't get back. My personality may also be a fit: I'm very much a measure twice, cut once kind of person. I tend write my algorithms in pseudo code and sketch my data structures on paper before I touch the keyboard, so even in my "get it done" language I don't immediately just start coding always.

deleted 4y ago
[deleted]

root_axis 4y ago

> I have encountered many situations where perfectly reasonable, zero copy, memory management that would be completely normal, fast and safe in C So you think. It doesn't matter how smart you think you are, statistically speaking you're not smarter than a compiler.

francasso 4y ago
I think you are overestimating the expressive power of lifetime annotations in rust, and how smart the borrow checker is
- estebank 4y ago
  Anything you can express in C, you can in Rust. When it comes to pointer tricks you might have to use unsafe, but that is part of the language.
  - platinumrad 4y ago
    If only 50% of the community didn't think it was their job to scream at complete strangers for using that part of the language.
    - nu11ptr 4y ago
      Agreed (unfortunately). There is too much of an obsession in avoiding unsafe at all costs in my opinion. When you consider all C/C++ is effectively written in an unsafe block then it seems a bit ludicrous to assume you would never ever use unsafe in tight, performant code.

easterncalculus 4y ago

Seeing some of the hassles with creating basic stuff like a linked list is part of the reason I have yet to use it seriously. I think I will eventually, but I certainly won't act like it doesn't come with a cost or that it always pays off.