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I think Rust is mostly about safety in the same way that skydiving is mostly about safety. Having safety features that you know you can rely on allows you to ta

I think Rust is mostly about safety in the same way that skydiving is mostly about safety. Having safety features that you know you can rely on allows you to take risks that you normally wouldn't in order to accomplish some really awesome things. (I guess in this analogy C is a parachute that you have to open manually, while Rust is a parachute that always opens at exactly the right altitude, but isn't any heavier than a normal parachute.)

dom0 10y ago
A lot of C libraries and applications are more like a parachute that was folded by someone who saw a two minute video about parachute folding a couple years ago.
nercury 10y ago
Rust safety is ultimately a productivity boost. For example, if I have a big string, I may create a hashmap where both keys and values are references to some portions to that original string. Then, I may pass this hashmap to another function that will transform this hashmap into structs that contain reused portions of those string references. Rust compiler will make sure that the original string is not destroyed or moved in any way in memory while this is happening. While it is certainly possible to do this in C and C++, the development cost there is way higher. In C++, one would be sensible to stick to a slower version that copies and allocates data, unless he/she is really sure that the need for performance justifies the code complication. Meanwhile, juggling the references this way in Rust is common and almost sloppy: the hashmap contains references to strings because it was probably created from iterator that iterated over references. The developer might not even need to notice it unless the string reference in result might be kept around longer than original. The compiler will tell about the type mismatch, and the developer will then create a new string from the reference, and then he/she will move on. There is a similar story when such code needs to be refactored. The word "sloppy" still works here, but in a good way: offloading "being very, very careful" stuff to compiler is deliciously fun.
- Manishearth 10y ago
  I wrote about this concept a bit in http://manishearth.github.io/blog/2015/05/03/where-rust-really-shines/ http://manishearth.github.io/blog/2015/05/03/where-rust-real..., with an example of a situation where in Rust I was able to make things work but in C++ I'd be totally terrified and use a shared_ptr or something. I like to say that Rust lets you toe the line perfectly, and dance near it as much as you want. C++ does not, since you're afraid you may accidentally cross it.
  - newsat13 10y ago
    Is that a joke? Just doing a cursory reading of your blog post was terrifying to me and I could hardly understand why things are so complicated. It almost make it seem like programming is some 'puzzle' (I feel same way about boost library).
    - nercury 10y ago
      Few recent posts that I can see are about the compiler internals, design of a tracing GC and a crypto problem. These things might just be complicated anyway :)
    - Manishearth 10y ago
      What did you find complicated or terrifying there? The fact that the code was complicated was sort of the point; the generic deriving code in the Rust compiler is in general a very tricky and confusing area and pretty complicated to deal with. In C++ I would have been very careful around code like this and not introduced new pointers. In Rust, I could do this without being afraid of memory issues. You're not supposed to understand the actual code in the blog post; there's heaps of context and explanations of compiler internals I didn't want to do. I tried to make it clear what task I wanted to do, and how the compiler helped me carry it out; the code is just there to give a better idea of what was going on. If you read closely I do mention that a lot of things should be ignored, there. The post also walks through the explanations of why the lifetimes work out that way, but that's more for the readers' edification -- I didn't need to actually figure anything out whilst working on it; the explanations are something I thought about later.
zerofan 10y ago
Have you done much skydiving? I used to go three days a week, for a couple years, between 4-10 jumps a day at a place that had world class experts. My experience is that only beginning skydivers are constantly preaching safety. They go around (vocally) judging everything they see, and I think they do it because it alleviates their own fear. Instructors would teach safety, but really only to their own students. I think the safety aspect of Rust appeals to a lot of beginning programmers. They can feel safer looking down their nose at us dangerous C or C++ programmers. > Rust is a parachute that always opens at exactly the right altitude This isn't a good metaphor. Frequently it's safer to pull higher, and on some occasions, you're safer opening lower than you had planned... I think a canopy that always opened at the prescribed height would cause many unnecessary deaths. That doesn't say anything about Rust, one way or the other.
- kibwen 10y ago
  > I think the safety aspect of Rust appeals to a lot of beginning programmers. Is that a bad thing? All programmers start as beginners, and if C is too painful to begin with then they'll learn via an easier language, and then comfortably spend their whole careers using those easier languages. If we want to expand the field of systems programmers organically, then we need to make tools that don't punish beginning programmers. > They can feel safer looking down their nose at us dangerous C or C++ programmers. What makes you feel like anyone's looking down their noses at you? Every language in history has been made to address the perceived flaws of some prior language. Safety is a crucial selling point for a huge chunk of people, and C and C++ have failed to appeal to this market. Just because safety isn't a priority for you doesn't mean that the people for whom it is a priority are suddenly pretentious.
  - zerofan 10y ago
    > > I think the safety aspect of Rust appeals to a lot of beginning programmers. > Is that a bad thing? The appeal to beginners is fine, maybe even a good thing, but the condescending comments from beginners is a lot like listening to a teenager who thinks they know everything. > What makes you feel like anyone's looking down their noses at you? There're are no shortage of obnoxious comments from beginning Rust users here and on Reddit. If you can't see them, it might be because you're aligned with that point of view. A recent one implied the whole world is going to end because of Heartbleed-like exploits. Don't they realize that despite the occasional high profile exploits, the world is generally running just fine? Don't they realize that the OpenSSL developers would've probably used pools of dirty memory to avoid allocation costs and unsafe blocks to avoid bounds checking had they developed that code in Rust? They got bit by sloppy optimization, and Rust isn't immune to that. I really wish people weren't so afraid of everything that achieving safety is their primary goal. > Just because safety isn't a priority for you doesn't mean that the people for whom it is a priority are suddenly pretentious. It's not pretentious if you make your own decision for your own project. It's not even pretentious to spread the good word and say how much you like Rust. It is very pretentious and condescending when you say something like in Graydon's article: """When someone says they "don't have safety problems" in C++, I am astonished: a statement that must be made in ignorance, if not outright negligence.""" Are you going to stand by that sentence? You probably should, because the newbies will love you for it, and it might help increase adoption of your language. It really shouldn't matter if you alienate a few of us old-timers who really don't have safety problems in C++. To be clear, I like Rust. I've been following it for years, and I'm disappointed that it's not an adequate replacement for C++ (which I really don't like).

dom0 10y ago

A lot of C libraries and applications are more like a parachute that was folded by someone who saw a two minute video about parachute folding a couple years ago.

nercury 10y ago

Rust safety is ultimately a productivity boost. For example, if I have a big string, I may create a hashmap where both keys and values are references to some portions to that original string. Then, I may pass this hashmap to another function that will transform this hashmap into structs that contain reused portions of those string references. Rust compiler will make sure that the original string is not destroyed or moved in any way in memory while this is happening. While it is certainly possible to do this in C and C++, the development cost there is way higher. In C++, one would be sensible to stick to a slower version that copies and allocates data, unless he/she is really sure that the need for performance justifies the code complication. Meanwhile, juggling the references this way in Rust is common and almost sloppy: the hashmap contains references to strings because it was probably created from iterator that iterated over references. The developer might not even need to notice it unless the string reference in result might be kept around longer than original. The compiler will tell about the type mismatch, and the developer will then create a new string from the reference, and then he/she will move on. There is a similar story when such code needs to be refactored. The word "sloppy" still works here, but in a good way: offloading "being very, very careful" stuff to compiler is deliciously fun.

Manishearth 10y ago
I wrote about this concept a bit in http://manishearth.github.io/blog/2015/05/03/where-rust-really-shines/ http://manishearth.github.io/blog/2015/05/03/where-rust-real..., with an example of a situation where in Rust I was able to make things work but in C++ I'd be totally terrified and use a shared_ptr or something. I like to say that Rust lets you toe the line perfectly, and dance near it as much as you want. C++ does not, since you're afraid you may accidentally cross it.
- newsat13 10y ago
  Is that a joke? Just doing a cursory reading of your blog post was terrifying to me and I could hardly understand why things are so complicated. It almost make it seem like programming is some 'puzzle' (I feel same way about boost library).
  - nercury 10y ago
    Few recent posts that I can see are about the compiler internals, design of a tracing GC and a crypto problem. These things might just be complicated anyway :)
  - Manishearth 10y ago
    What did you find complicated or terrifying there? The fact that the code was complicated was sort of the point; the generic deriving code in the Rust compiler is in general a very tricky and confusing area and pretty complicated to deal with. In C++ I would have been very careful around code like this and not introduced new pointers. In Rust, I could do this without being afraid of memory issues. You're not supposed to understand the actual code in the blog post; there's heaps of context and explanations of compiler internals I didn't want to do. I tried to make it clear what task I wanted to do, and how the compiler helped me carry it out; the code is just there to give a better idea of what was going on. If you read closely I do mention that a lot of things should be ignored, there. The post also walks through the explanations of why the lifetimes work out that way, but that's more for the readers' edification -- I didn't need to actually figure anything out whilst working on it; the explanations are something I thought about later.

zerofan 10y ago

Have you done much skydiving? I used to go three days a week, for a couple years, between 4-10 jumps a day at a place that had world class experts. My experience is that only beginning skydivers are constantly preaching safety. They go around (vocally) judging everything they see, and I think they do it because it alleviates their own fear. Instructors would teach safety, but really only to their own students. I think the safety aspect of Rust appeals to a lot of beginning programmers. They can feel safer looking down their nose at us dangerous C or C++ programmers. > Rust is a parachute that always opens at exactly the right altitude This isn't a good metaphor. Frequently it's safer to pull higher, and on some occasions, you're safer opening lower than you had planned... I think a canopy that always opened at the prescribed height would cause many unnecessary deaths. That doesn't say anything about Rust, one way or the other.

kibwen 10y ago
> I think the safety aspect of Rust appeals to a lot of beginning programmers. Is that a bad thing? All programmers start as beginners, and if C is too painful to begin with then they'll learn via an easier language, and then comfortably spend their whole careers using those easier languages. If we want to expand the field of systems programmers organically, then we need to make tools that don't punish beginning programmers. > They can feel safer looking down their nose at us dangerous C or C++ programmers. What makes you feel like anyone's looking down their noses at you? Every language in history has been made to address the perceived flaws of some prior language. Safety is a crucial selling point for a huge chunk of people, and C and C++ have failed to appeal to this market. Just because safety isn't a priority for you doesn't mean that the people for whom it is a priority are suddenly pretentious.
- zerofan 10y ago
  > > I think the safety aspect of Rust appeals to a lot of beginning programmers. > Is that a bad thing? The appeal to beginners is fine, maybe even a good thing, but the condescending comments from beginners is a lot like listening to a teenager who thinks they know everything. > What makes you feel like anyone's looking down their noses at you? There're are no shortage of obnoxious comments from beginning Rust users here and on Reddit. If you can't see them, it might be because you're aligned with that point of view. A recent one implied the whole world is going to end because of Heartbleed-like exploits. Don't they realize that despite the occasional high profile exploits, the world is generally running just fine? Don't they realize that the OpenSSL developers would've probably used pools of dirty memory to avoid allocation costs and unsafe blocks to avoid bounds checking had they developed that code in Rust? They got bit by sloppy optimization, and Rust isn't immune to that. I really wish people weren't so afraid of everything that achieving safety is their primary goal. > Just because safety isn't a priority for you doesn't mean that the people for whom it is a priority are suddenly pretentious. It's not pretentious if you make your own decision for your own project. It's not even pretentious to spread the good word and say how much you like Rust. It is very pretentious and condescending when you say something like in Graydon's article: """When someone says they "don't have safety problems" in C++, I am astonished: a statement that must be made in ignorance, if not outright negligence.""" Are you going to stand by that sentence? You probably should, because the newbies will love you for it, and it might help increase adoption of your language. It really shouldn't matter if you alienate a few of us old-timers who really don't have safety problems in C++. To be clear, I like Rust. I've been following it for years, and I'm disappointed that it's not an adequate replacement for C++ (which I really don't like).