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First, the expressiveness is all there. You just need to explicitly say you are responsible by using unsafe blocks. So risky pointer and allocation logic become

First, the expressiveness is all there. You just need to explicitly say you are responsible by using unsafe blocks. So risky pointer and allocation logic becomes the programmer's job, not the borrow checker. Second, this article only considers the costs of a stricter borrow checker, not the benefits. It will be more work for the coder to have to think about how allocation and ownership is communicates. But I've been through much bigger headaches in production code at inconvenient times (for the business plan) due to dangling pointers, multi-writer concurrency bugs, and ill-defined memory models in software designs. Even if Rust is much harder than alternatives instead of just different, and even if that's inherent in borrow checking, it's not clear that it's still not worth it in the long run.

jackmott 10y ago
It might be worth it over C++, but assuming the task at hand is not hindered by garbage collection, is it ever worth it over an ML style language? It certainly takes a lot more typing to get things done.
- pmoriarty 10y ago
  I think it's always worth it to learn new paradigms. They expand your view of what's possible, and give you a richer understanding of the other languages you already know, understanding some of the tradeoffs they made, and give you other conceptual and practical tools in your toolbox. It's much like visiting other, radically different countries than the ones you've been brought up in. Even if you don't wind up moving there permanently, you'll be richer for the experience.
Bartweiss 10y ago
> Even if Rust is much harder than alternatives instead of just different, and even if that's inherent in borrow checking, it's not clear that it's still not worth it in the long run. One obvious argument is that Rust frontloads its difficulty. It's a terrible tool for most 30 line tasks, simply because the majority of your work will go into arguing with the compiler. But that's true of a great many tools - if there's an adequate payoff in safety and comprehensibility at scale, they can still be worthwhile. That doesn't solve the learning-and-usage problem, though. Most of us are aware that the explosion of dangerous-at-scale tools like Javascript is largely because no one adopts a language that's unfriendly until you reach enterprise sizes. Even if Rust is "worth it", it's unlikely to catch on while the learning experience feels like pulling teeth.
- bluejekyll 10y ago
  > It's a terrible tool for most 30 line tasks, simply because the majority of your work will go into arguing with the compiler. This arguing with the compiler is really only while you are learning Rust and it's nuances. For me the first two weeks were this way, then I started thinking more in Rust terms. Now I rarely deal with the borrow checker at all, but I do end up in some complex type situations. You're spot on with the frontloads difficulty. Honestly though, I can't think of any language that I've learned that in under a few weeks I knew how to properly do things in the language. Python was this way for me. My code looked like C when I started with it, and then I learned after a few weeks about 'with' and 'yield' and started writing real code. Rust is worth the initial investment, but the first two weeks will require some perseverance.
  - spullara 10y ago
    I think the difference is that while you are coding Python in a C style the code is working. The front loaded nature of Rust means that you are in a constant fight to get something to run.
    - bluejekyll 10y ago
      Yes, and I understand how frustrating it can be, I had to learn it, too. My only point is that after you spend the time with it, the cognitive load becomes a lot less and you've learned some new things about programming at the same time.
      - spullara 10y ago
        I believe this. However, my concern is that the number of people willing to make it through that learning curve is small and will limit the adoption of Rust.
        bluejekyll 10y ago
        I'm hoping that things like the Rust Language Server and it's integration into some of the IDE's out there will help with the initial learning curve; already the rustc error output is a million times better than when I started with it. I definitely share your concern; for me, Rust was like putting on a glove perfectly shaped for my hand. It works and prevents every basic pattern that it took 10 years to learn and start applying to all my code thereafter. If I had Rust all those years ago, it would have saved me a ton of time... but I probably would have turned my nose up at it, b/c I wouldn't have had the experience to understand what it was saving me from. So yes, I want the learning curve to be lower, but not at the expense of losing all of the safety it brings to developing fast and reliable software.
rbehrends 10y ago
> First, the expressiveness is all there. You just need to explicitly say you are responsible by using unsafe blocks. So risky pointer and allocation logic becomes the programmer's job, not the borrow checker. No, unsafe would be overkill and if you needed unsafe, it would put Rust at a massive disadvantage vis-à-vis garbage-collected languages. Simply put, Rust doesn't handle multiple ownership well. It results in syntactic bloat and/or runtime overhead. But multiple ownership occurs naturally in a number of real-world programs. > Second, this article only considers the costs of a stricter borrow checker, not the benefits. This is why I very specifically mentioned that it's a tradeoff.
- bluejekyll 10y ago
  I think you're implication here is that other languages do handle multiple ownership well. What I think you find in Rust, is that the guarantees you need to make when using unsafe in these limited situations, are the exact same guarantees you need to make in a language like C or C++. Destroying a circular list takes some thought to make sure you don't double free, same as Rust. Rust just makes those sections of code very explicit and calls your attention to it, while in C you may end up with a segfault, or worse a program that only shows odd bugs during runtime. At least Rust is telling you that you need to put some extra thought in this section.
  - rbehrends 10y ago
    Your assumption seems to be that I'm talking about languages with manual memory management. I'm not; I'm talking about garbage-collected languages, where you get memory safety automatically, regardless of ownership rules. In fact, C++ has some of the same problems that Rust has when it comes to multiple ownership.
    - kaoD 10y ago
      Then use https://github.com/Manishearth/rust-gc https://github.com/Manishearth/rust-gc if you're willing to pay the price of a GC (still experimental). Or better, stick to a GC'ed language. If you don't need manual memory management, it's obviously going to be a burden. There are still use cases for manual memory management though, and that's where Rust comes in. Use the right tool for the job.

jackmott 10y ago

It might be worth it over C++, but assuming the task at hand is not hindered by garbage collection, is it ever worth it over an ML style language? It certainly takes a lot more typing to get things done.

pmoriarty 10y ago
I think it's always worth it to learn new paradigms. They expand your view of what's possible, and give you a richer understanding of the other languages you already know, understanding some of the tradeoffs they made, and give you other conceptual and practical tools in your toolbox. It's much like visiting other, radically different countries than the ones you've been brought up in. Even if you don't wind up moving there permanently, you'll be richer for the experience.

Bartweiss 10y ago

> Even if Rust is much harder than alternatives instead of just different, and even if that's inherent in borrow checking, it's not clear that it's still not worth it in the long run. One obvious argument is that Rust frontloads its difficulty. It's a terrible tool for most 30 line tasks, simply because the majority of your work will go into arguing with the compiler. But that's true of a great many tools - if there's an adequate payoff in safety and comprehensibility at scale, they can still be worthwhile. That doesn't solve the learning-and-usage problem, though. Most of us are aware that the explosion of dangerous-at-scale tools like Javascript is largely because no one adopts a language that's unfriendly until you reach enterprise sizes. Even if Rust is "worth it", it's unlikely to catch on while the learning experience feels like pulling teeth.

bluejekyll 10y ago
> It's a terrible tool for most 30 line tasks, simply because the majority of your work will go into arguing with the compiler. This arguing with the compiler is really only while you are learning Rust and it's nuances. For me the first two weeks were this way, then I started thinking more in Rust terms. Now I rarely deal with the borrow checker at all, but I do end up in some complex type situations. You're spot on with the frontloads difficulty. Honestly though, I can't think of any language that I've learned that in under a few weeks I knew how to properly do things in the language. Python was this way for me. My code looked like C when I started with it, and then I learned after a few weeks about 'with' and 'yield' and started writing real code. Rust is worth the initial investment, but the first two weeks will require some perseverance.
- spullara 10y ago
  I think the difference is that while you are coding Python in a C style the code is working. The front loaded nature of Rust means that you are in a constant fight to get something to run.
  - bluejekyll 10y ago
    Yes, and I understand how frustrating it can be, I had to learn it, too. My only point is that after you spend the time with it, the cognitive load becomes a lot less and you've learned some new things about programming at the same time.
    - spullara 10y ago
      I believe this. However, my concern is that the number of people willing to make it through that learning curve is small and will limit the adoption of Rust.
      - bluejekyll 10y ago
        I'm hoping that things like the Rust Language Server and it's integration into some of the IDE's out there will help with the initial learning curve; already the rustc error output is a million times better than when I started with it. I definitely share your concern; for me, Rust was like putting on a glove perfectly shaped for my hand. It works and prevents every basic pattern that it took 10 years to learn and start applying to all my code thereafter. If I had Rust all those years ago, it would have saved me a ton of time... but I probably would have turned my nose up at it, b/c I wouldn't have had the experience to understand what it was saving me from. So yes, I want the learning curve to be lower, but not at the expense of losing all of the safety it brings to developing fast and reliable software.

rbehrends 10y ago

> First, the expressiveness is all there. You just need to explicitly say you are responsible by using unsafe blocks. So risky pointer and allocation logic becomes the programmer's job, not the borrow checker. No, unsafe would be overkill and if you needed unsafe, it would put Rust at a massive disadvantage vis-à-vis garbage-collected languages. Simply put, Rust doesn't handle multiple ownership well. It results in syntactic bloat and/or runtime overhead. But multiple ownership occurs naturally in a number of real-world programs. > Second, this article only considers the costs of a stricter borrow checker, not the benefits. This is why I very specifically mentioned that it's a tradeoff.

bluejekyll 10y ago
I think you're implication here is that other languages do handle multiple ownership well. What I think you find in Rust, is that the guarantees you need to make when using unsafe in these limited situations, are the exact same guarantees you need to make in a language like C or C++. Destroying a circular list takes some thought to make sure you don't double free, same as Rust. Rust just makes those sections of code very explicit and calls your attention to it, while in C you may end up with a segfault, or worse a program that only shows odd bugs during runtime. At least Rust is telling you that you need to put some extra thought in this section.
- rbehrends 10y ago
  Your assumption seems to be that I'm talking about languages with manual memory management. I'm not; I'm talking about garbage-collected languages, where you get memory safety automatically, regardless of ownership rules. In fact, C++ has some of the same problems that Rust has when it comes to multiple ownership.
  - kaoD 10y ago
    Then use https://github.com/Manishearth/rust-gc https://github.com/Manishearth/rust-gc if you're willing to pay the price of a GC (still experimental). Or better, stick to a GC'ed language. If you don't need manual memory management, it's obviously going to be a burden. There are still use cases for manual memory management though, and that's where Rust comes in. Use the right tool for the job.