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A 30-minute Introduction to Rust

244 points by aabelha 12y ago

mattdw 12y ago
I've only ever used GCed (and largely dynamic) languages up until now (Python, JS and Clojure primarily); C is alien and C++ is frankly terrifying. With all that, I've been having a ball using Rust to solve Project Euler problems, with astonishing speed compared to what I'm used to. It doesn't quite have all the libs you might want for general development yet, but for the things it's currently equipped for it's a lot of fun, and surprisingly easy. (Up until I find myself in a quagmire of lifetime problems of my own making. Looking forward to the coming lifetimes inference enhancement.) It's a surprisingly reasonable functional programming environment too.
- Pacabel 12y ago
  Why do you see C++ as "terrifying"? Yes, it is a very powerful language and there can be a lot to it, but it shouldn't "terrify" you. These days, it's generally quite easy to avoid much of its C heritage (including potential security pitfalls) if using the so-called "modern C++" techniques, but the extra power and flexibility is still there if you do ever need it. There are numerous ways of easily avoiding manual memory (or other resource) management, too. The STL and Boost, among numerous other libraries that are out there, offer lots of convenient, high level functionality. The portability of C++ code is often quite excellent, the language and its standard libraries are quite stable, and there are multiple commercial-grade implementations from numerous vendors/projects. You probably won't find anything else that gives you a high degree of performance along with high level abstractions, while also giving you the peace of mind that your code will still compile just fine years or even decades from now. While it's certainly possible to to overboard and misuse C++ to a point where it causes serious problems, one of the best things about C++ is that it doesn't force you to do that. You generally don't pay for what you don't use, and it's certainly possible to use a very effective subset of the language much as one might use Java or C#, or even Python and JavaScript. I'd say that C++ is even easier to use than JavaScript is. C++ is much more sensible in so many ways, and nowhere near as quirky or just outright broken in fundamental ways like JavaScript, while also providing at least some type safety and other compile-time checks. If you want a stable, portable, safe, well-supported language that offers high level functionality without the performance tradeoffs of other languages, then I think that a modern subset of C++ could very well be exactly what you're looking for.
  - pcwalton 12y ago
    C++ is not safe in the same sense that Rust is. Without the use of "unsafe", Rust is designed to never segfault or have undefined behavior, ever. Even a modern subset of C++ cannot make the same guarantees (consider iterator invalidation, etc.)
    - Pacabel 12y ago
      I'll gladly use modern C++ techniques and a bit of care, even if that means only getting say 90% or 95% of the safety that Rust potentially offers offers, if it also means that I can get my code written today, and I can trust that it'll still compile unchanged tomorrow, next week, and probably a decade from now. I think it's great what Rust could potentially offer software developers. But it's still pretty theoretical at this point. The language and standard libraries aren't sufficiently stable enough for serious, long-term use, currently. I hear we may start to see the beginning of such stability at the end of the year, but until it actually happens, Rust isn't very useful, while C++ is.
      - baq 12y ago
        if C++ doesn't terrify you, you're probably using it too much. C++ is the most complex programming language ever invented.
        Pacabel 12y ago
        Yes, it's a big language, but the complexity is at least justifiable, and generally comprehensible. C++ gives you immense power and a huge range of functionality to choose from, and some of the complexity arises from this. It has a very long history, which also contributes to the complexity. And it's first and foremost a pragmatic language, which of course brings in some complexity in order to deal with the inherent complexity of reality. If something is seen as "complex" in C++, there's usually a good, or at least understandable, reason for this. You can usually find technical documents or discussion that justify why things are they way that they are, and the reasoning is usually quite sound. And in many cases, it's possible to safely ignore or just not use large portions of the complexity that C++ offers without facing any sort of a penalty or harm. It's very different from the complexity that languages like JavaScript or PHP bring. The complexity there is usually unjustifiable, and often due to very rushed work, a lack of understanding and poor design, or a lack of care and consistency. They suffer from serious flaws and complexity that were not justified when introduced, and were subsequently not cleaned up or fixed once recognized. They suffer from harmful complexity, while C++ offers beneficial complexity.
- steveklabnik 12y ago
  I would looooove any insight that you have on making the docs better for people who haven't done systems programming before. If you've ever got the time to type out a few thoughts, my email is in my profile.
  - jsmthrowaway 12y ago
    Assuming you wrote this, you lost me in the book analogy. Once you wrote "let's ignore programming for a moment" I thought to myself, why am I here? And why are we talking about ownership? How do I set up a tool chain and write hello world? This doesn't strike me as a 30 minute intro to Rust. More like a quick guide to what sets Rust apart from C. Perhaps my expectations would be different with a different title ("How Rust can benefit you as a working C++ dev")
    - steveklabnik 12y ago
      > Perhaps my expectations would be different with a different title Hmm yes, I will think about it. Ownership is Rust's most important and unique concept, so an intro to ownership _is_ an intro to Rust. I will think about how to make this more clear.
      - Scramblejams 12y ago
        I had no problem with the book analogy. I've been hovering around the periphery of Rust for a while, waiting until I understood the ownership thing before I move into it more seriously. Thanks for writing this! I think it was a solid step in the direction of clearly explaining ownership. I know more than I did before and I'm looking forward to reading your next piece on it. Good work.
        steveklabnik 12y ago
        Thank you! The URL to watch is http://doc.rust-lang.org/guide.html http://doc.rust-lang.org/guide.html . I'm working on it every day. Two more sections should land tonight, and I'm writing the next one as we speak... don't hesitate to ping me with ways the docs could be better, either on IRC, email, or just opening an issue on the repo and CC'ing me.
geoffroy 12y ago
I enjoyed reading this !
steveklabnik 12y ago
I wrote this a while back as a blog post, it ended up being the actual intro. I hope to go over it again soon, and make it better. There's nothing super wrong with it, but you can always improve! Feedback welcome. Oh, and we had a big discussion last time: https://news.ycombinator.com/item?id=7051835 https://news.ycombinator.com/item?id=7051835
- letstryagain 12y ago
  I knew this was your work! EDIT: concurrency.rs:12:20: 12:27 error: use of moved value: 'numbers' Is this a compile-time or a run-time error?
  - pcwalton 12y ago
    Compile-time.
XorNot 12y ago
I gotta say, reading this actually made me really excited about Rust. C++ without the annoying memory management but no GC-overhead sounds like a dream.
- bjz_ 12y ago
  Just to temper your enthusiasm, the compiler errors can sometimes be irritating, especially when you want to do something the you are pretty sure will be safe. But on the whole if you work with it the pay-off is well worth the minor annoyances. Having the compiler always check your code for memory safety is a huge win for refactoring - C or C++ code bases get really brittle over time as developers forget what is actually going on. I would also say that the number of errors you encounter over time reduce as you gain an intuition for the rules.
  - dbaupp 12y ago
    > especially when you want to do something the you are pretty sure will be safe (It's worth noting that often the compiler is complaining because it actually isn't safe.)
    - chrismorgan 12y ago
      Indeed, I’ve been certain that something that it’s not letting me do is safe, only to realise a bit later that actually it was right in a subtle way. There are certainly some valid things that the compiler will forbid which you then need to work around instead, but by and large I trust the compiler to be right more than I trust myself. (Bear in mind, still, that these sorts of arguments of Rust’s superiority in such things are frequently only applicable for comparisons with languages like C++; often they are the sorts of things that a managed language would not have a problem with, though also not infrequently it would lead to things like data race.)
    - bjz_ 12y ago
      Yes! It is often showing a flaw in your mental model, which can be painful at first, but once solved it will ultimately result in more reliable code.
shawkinaw 12y ago
Is the language stable enough to learn yet (given that I won't be really using it immediately)? I've been putting off looking at it because it seemed very much in flux.
- bjz_ 12y ago
  For learning I would say it is. The biggest thing at the moment is API changes. But the team is now pushing to put stability attributes on all modules and marking deprecated items as such for a time before their removal (these emit warnings if used). I would highly recommend using the nightlies from http://rust-lang.org/ http://rust-lang.org/. A list of the docs can be found here: http://doc.rust-lang.org/index.html http://doc.rust-lang.org/index.html Reddit is also good for keeping up to date on news: http://www.reddit.com/r/rust http://www.reddit.com/r/rust Also, IRC is your friend! Join #rust at irc.mozilla.org, and feel free to ask questions. The community is very friendly and willing to help.
- Argorak 12y ago
  There is a very special fun in learning Rust. It isn't stable in the sense that your code from last week will compile this week. On the other hand, it is currently stable enough that all the major concepts are there and most changes are either syntax or API. So reading up on the changes of last week and some search and replace cover most things. Also, most API changes now are introduced through deprecations. All breaking language changes have an RFC process. The great thing is to see a language while it is still being shaped. Have something you don't like or something that is incredibly clunky? Get involved! The barrier will never be lower. Backwards compatibility is not a thing yet! If the change makes sense and you can muster the resources for it, there is no one holding you back. Code review for pull requests is also awesome, all of my pull requests were accepted on the second or the third try - but for the better! On top of that, it is a really interesting language on it's own right with interesting concepts worth learning.
deleted 12y ago
[deleted]
zimbatm 12y ago
How much cognitive overhead is it to think about ownership all the time once you get used to it ? Coming from a GC-languages background I had a hard time thinking in those terms last time I played with it. I ended up having .clone() littered all over the place :)
- pcwalton 12y ago
  I find that it's no more mental overhead than it is in C. The nice thing is that the development cycle ends up being faster than C for me because I don't have to spend as much time in front of the debugger.
  - deleted 12y ago
    [deleted]
- chrismorgan 12y ago
  I don’t find that I need to think about it often at all. And very often I can get away with thinking about it less than I should, because if I make a mistake, the compiler will pull me up short. ☺ When writing libraries, you will typically need to think about ownership more frequently than when writing applications, but it’s normally not at all problematic.
- aidenn0 12y ago
  Writing libraries you need to think about it a lot it really informs the choices for datastructures you make. Other than that, it's considerably easier than other non-managed languages (e.g. C, C++, Pascal)
zwieback 12y ago
I like this a lot, the right level to get an idea of what Rust is about. The last example illustrates that concurrency is complex no matter what language you use - the code ends up reflecting the scaffolding enabling concurrency and the actual work ends up buried inside. That said, I like what I see.
Demagog 12y ago
Frankly, probably the best introduction to Rust is "Rust by example" [1] This is much more in depth + possibility of running code on site. I don't understand why rust site doesn't have links to this project. [1] http://rustbyexample.com/ http://rustbyexample.com/
- dbaupp 12y ago
  http://doc.rust-lang.org/master/#external-documentation http://doc.rust-lang.org/master/#external-documentation
- steveklabnik 12y ago
  > This is much more in depth This is Hacker News, so I'll explain it to you this way: this is specifically _not_ in depth. Have you ever done sales? The idea is that you need to figure out if your customer wants to buy as quickly as possible, and if they don't, move on. If they do, _then_ you move into the longform stuff. If your customer isn't going to buy, it wastes both you and their time. The idea of this short introduction is to split you into one of two camps: "I want to know more about Rust," or "ewww." If you're in camp one, heading over to the tutorial or Rust by Example is great!
  - AnimalMuppet 12y ago
    Yeah, an "in 30 minutes" article is probably not going to give you "in depth". It's not meant to.
njharman 12y ago
Who is "behind" Rust? A company, consortium, academics, BDFL? http://www.rust-lang.org/ http://www.rust-lang.org/ doesn't have an about page. Didn't see answer listed in the FAQ.
- steveklabnik 12y ago
  Mozilla is behind most of it. The original creator has already left the project, so we don't have a BDFL. There is a core team, mostly of Mozilla employees. Tilde has been contracted to do the package manager, I have been contracted to do documentation. There's a pretty significant community for a language so young, our IRC channel has ~600 people in it.
- bjz_ 12y ago
  Mozilla is the big driving force, with a small, dedicated group of developers from Mozilla doing a huge amount of the boring 'grunt work', and also making the hard decisions when it comes to design. The community is a huge driving force though, with lots of great contributions being landed all the time.
blub 12y ago
Out of curiosity I implemented the two examples in C++11. For the number add I used a unique_ptr (although returning by value would be better in every way). For the shared state I used async with a lamba that calls transform and returns the modified vector through a future. This doesn't execute in parallel for each for loop though. I think something like Arc can be coded in C++ too - template wrapper that returns a RAII lock whick unlocks on scope end. I think the only big difference is that some errors in Rust are happening at compile time. In the first case the original buggy code was triggering only a warning in C++. Right now the extra compile-safety of Rust is IMO not worth giving up the other benefits of C++, especially now that C++11 with some extra static checking and good guidelines can go a long way.
- steveklabnik 12y ago
  Box<T> is roughly equivalent to unique_ptr, and you're correct, returning by value would be better. Rust idiom is to use stack allocation and borrowing wherever possible. > I think the only big difference is that some errors in Rust are happening at compile time. This is true in these examples, except maybe the enforcement of not using a pointer after you've sent it to a task. That said, there are other examples, like iterator invalidation, where Rust is completely memory safe, unlike C++. Furthermore, Rust has significantly less undefined behavior and odd edge cases. These are in C++ for good reason, but they're still there. > with some extra static checking and good guidelines can go a long way. They can go a long way, and that may be enough for you. Big applications continue to have security issues due to problems that Rust would prevent, though: in the last Pwn2Own, all of Firefox's bugs would not have been possible in Rust, for example.
  - blub 12y ago
    Thanks for the details. In all honesty I am probably not a target for Rust anyway, I almost never use C++ for systems programming, but rather for (cross-platform) application development. It would seem that neither Rust nor Go serve this area and probably do not intend to do it either.
    - 12y ago
pkulak 12y ago
Wow, is Rust ever changing quickly. I think I read some docs a few months ago and most of this was different. It's gotten better though. All that punctuation for different pointer types was a bit too much. And this way of using mutexes as accessors that unlock automatically when they leave scope is brilliant. I can't wait for Rust to be "done" (and get some kick-ass HTTP support).
- steveklabnik 12y ago
  Thanks! We have slowly been removing the sigils. As a quick reference: let x = ~5; let y = @5; is now let x = box 5; let y = box(Rc) 5; (though obviously, boxing an integer is silly) > and get some kick-ass HTTP support http://arewewebyet.com/ http://arewewebyet.com/
peaton 12y ago
As someone fairly new to systems programming, I can still see why you'd want to pick a language like Rust over C. But can someone explain to me the difference between Rust and Erlang? They are both system languages, no? Erlang is much more established. But what are the key differences? And I'd ask, "which should I learn?", but that is generally not a great question...
- aidenn0 12y ago
  "Systems programming" is a broad term, so you are painting in too-broad strokes. I'm not super familiar with Erlang, so I may get some things wrong, but heres a few differences: Erlang prefers GC, wheras Rust tends to eschew it (it's available in a library). Erlang is dynamically typed where rust is statically typed. Erlang is single-assignment where rust uses a somewhat more nuanced lifetime system (though that is still changing). Erlang prefers communication over channels, while rust has immutable types that are safe to share.
  - peaton 12y ago
    Are there specific implementation models or areas or systems programming that favor (or have come to use more exclusively) Rust or Erlang?
    - steveklabnik 12y ago
      A significant one is that Rust has no GC, while Erlang does. This can matter if you're trying to build software that's very sensitive to random pauses, or embedded development. Another significant one is that Erlang has been used to make some of the most reliable software ever for the past few decades, and Rust is still pre-1.0.
      - peaton 12y ago
        I don't mean to sounds skeptic when I say this: could you list some of the software (or teams) that use Erlang?

244 points by aabelha 12y ago

I've only ever used GCed (and largely dynamic) languages up until now (Python, JS and Clojure primarily); C is alien and C++ is frankly terrifying. With all that, I've been having a ball using Rust to solve Project Euler problems, with astonishing speed compared to what I'm used to. It doesn't quite have all the libs you might want for general development yet, but for the things it's currently equipped for it's a lot of fun, and surprisingly easy. (Up until I find myself in a quagmire of lifetime problems of my own making. Looking forward to the coming lifetimes inference enhancement.) It's a surprisingly reasonable functional programming environment too.

Pacabel 12y ago
Why do you see C++ as "terrifying"? Yes, it is a very powerful language and there can be a lot to it, but it shouldn't "terrify" you. These days, it's generally quite easy to avoid much of its C heritage (including potential security pitfalls) if using the so-called "modern C++" techniques, but the extra power and flexibility is still there if you do ever need it. There are numerous ways of easily avoiding manual memory (or other resource) management, too. The STL and Boost, among numerous other libraries that are out there, offer lots of convenient, high level functionality. The portability of C++ code is often quite excellent, the language and its standard libraries are quite stable, and there are multiple commercial-grade implementations from numerous vendors/projects. You probably won't find anything else that gives you a high degree of performance along with high level abstractions, while also giving you the peace of mind that your code will still compile just fine years or even decades from now. While it's certainly possible to to overboard and misuse C++ to a point where it causes serious problems, one of the best things about C++ is that it doesn't force you to do that. You generally don't pay for what you don't use, and it's certainly possible to use a very effective subset of the language much as one might use Java or C#, or even Python and JavaScript. I'd say that C++ is even easier to use than JavaScript is. C++ is much more sensible in so many ways, and nowhere near as quirky or just outright broken in fundamental ways like JavaScript, while also providing at least some type safety and other compile-time checks. If you want a stable, portable, safe, well-supported language that offers high level functionality without the performance tradeoffs of other languages, then I think that a modern subset of C++ could very well be exactly what you're looking for.
- pcwalton 12y ago
  C++ is not safe in the same sense that Rust is. Without the use of "unsafe", Rust is designed to never segfault or have undefined behavior, ever. Even a modern subset of C++ cannot make the same guarantees (consider iterator invalidation, etc.)
  - Pacabel 12y ago
    I'll gladly use modern C++ techniques and a bit of care, even if that means only getting say 90% or 95% of the safety that Rust potentially offers offers, if it also means that I can get my code written today, and I can trust that it'll still compile unchanged tomorrow, next week, and probably a decade from now. I think it's great what Rust could potentially offer software developers. But it's still pretty theoretical at this point. The language and standard libraries aren't sufficiently stable enough for serious, long-term use, currently. I hear we may start to see the beginning of such stability at the end of the year, but until it actually happens, Rust isn't very useful, while C++ is.
    - baq 12y ago
      if C++ doesn't terrify you, you're probably using it too much. C++ is the most complex programming language ever invented.
      - Pacabel 12y ago
        Yes, it's a big language, but the complexity is at least justifiable, and generally comprehensible. C++ gives you immense power and a huge range of functionality to choose from, and some of the complexity arises from this. It has a very long history, which also contributes to the complexity. And it's first and foremost a pragmatic language, which of course brings in some complexity in order to deal with the inherent complexity of reality. If something is seen as "complex" in C++, there's usually a good, or at least understandable, reason for this. You can usually find technical documents or discussion that justify why things are they way that they are, and the reasoning is usually quite sound. And in many cases, it's possible to safely ignore or just not use large portions of the complexity that C++ offers without facing any sort of a penalty or harm. It's very different from the complexity that languages like JavaScript or PHP bring. The complexity there is usually unjustifiable, and often due to very rushed work, a lack of understanding and poor design, or a lack of care and consistency. They suffer from serious flaws and complexity that were not justified when introduced, and were subsequently not cleaned up or fixed once recognized. They suffer from harmful complexity, while C++ offers beneficial complexity.
steveklabnik 12y ago
I would looooove any insight that you have on making the docs better for people who haven't done systems programming before. If you've ever got the time to type out a few thoughts, my email is in my profile.
- jsmthrowaway 12y ago
  Assuming you wrote this, you lost me in the book analogy. Once you wrote "let's ignore programming for a moment" I thought to myself, why am I here? And why are we talking about ownership? How do I set up a tool chain and write hello world? This doesn't strike me as a 30 minute intro to Rust. More like a quick guide to what sets Rust apart from C. Perhaps my expectations would be different with a different title ("How Rust can benefit you as a working C++ dev")
  - steveklabnik 12y ago
    > Perhaps my expectations would be different with a different title Hmm yes, I will think about it. Ownership is Rust's most important and unique concept, so an intro to ownership _is_ an intro to Rust. I will think about how to make this more clear.
    - Scramblejams 12y ago
      I had no problem with the book analogy. I've been hovering around the periphery of Rust for a while, waiting until I understood the ownership thing before I move into it more seriously. Thanks for writing this! I think it was a solid step in the direction of clearly explaining ownership. I know more than I did before and I'm looking forward to reading your next piece on it. Good work.
      - steveklabnik 12y ago
        Thank you! The URL to watch is http://doc.rust-lang.org/guide.html http://doc.rust-lang.org/guide.html . I'm working on it every day. Two more sections should land tonight, and I'm writing the next one as we speak... don't hesitate to ping me with ways the docs could be better, either on IRC, email, or just opening an issue on the repo and CC'ing me.

geoffroy 12y ago

I enjoyed reading this !

steveklabnik 12y ago

I wrote this a while back as a blog post, it ended up being the actual intro. I hope to go over it again soon, and make it better. There's nothing super wrong with it, but you can always improve! Feedback welcome. Oh, and we had a big discussion last time: https://news.ycombinator.com/item?id=7051835 https://news.ycombinator.com/item?id=7051835

letstryagain 12y ago
I knew this was your work! EDIT: concurrency.rs:12:20: 12:27 error: use of moved value: 'numbers' Is this a compile-time or a run-time error?
- pcwalton 12y ago
  Compile-time.

XorNot 12y ago

I gotta say, reading this actually made me really excited about Rust. C++ without the annoying memory management but no GC-overhead sounds like a dream.

bjz_ 12y ago
Just to temper your enthusiasm, the compiler errors can sometimes be irritating, especially when you want to do something the you are pretty sure will be safe. But on the whole if you work with it the pay-off is well worth the minor annoyances. Having the compiler always check your code for memory safety is a huge win for refactoring - C or C++ code bases get really brittle over time as developers forget what is actually going on. I would also say that the number of errors you encounter over time reduce as you gain an intuition for the rules.
- dbaupp 12y ago
  > especially when you want to do something the you are pretty sure will be safe (It's worth noting that often the compiler is complaining because it actually isn't safe.)
  - chrismorgan 12y ago
    Indeed, I’ve been certain that something that it’s not letting me do is safe, only to realise a bit later that actually it was right in a subtle way. There are certainly some valid things that the compiler will forbid which you then need to work around instead, but by and large I trust the compiler to be right more than I trust myself. (Bear in mind, still, that these sorts of arguments of Rust’s superiority in such things are frequently only applicable for comparisons with languages like C++; often they are the sorts of things that a managed language would not have a problem with, though also not infrequently it would lead to things like data race.)
  - bjz_ 12y ago
    Yes! It is often showing a flaw in your mental model, which can be painful at first, but once solved it will ultimately result in more reliable code.

shawkinaw 12y ago

Is the language stable enough to learn yet (given that I won't be really using it immediately)? I've been putting off looking at it because it seemed very much in flux.

bjz_ 12y ago
For learning I would say it is. The biggest thing at the moment is API changes. But the team is now pushing to put stability attributes on all modules and marking deprecated items as such for a time before their removal (these emit warnings if used). I would highly recommend using the nightlies from http://rust-lang.org/ http://rust-lang.org/. A list of the docs can be found here: http://doc.rust-lang.org/index.html http://doc.rust-lang.org/index.html Reddit is also good for keeping up to date on news: http://www.reddit.com/r/rust http://www.reddit.com/r/rust Also, IRC is your friend! Join #rust at irc.mozilla.org, and feel free to ask questions. The community is very friendly and willing to help.
Argorak 12y ago
There is a very special fun in learning Rust. It isn't stable in the sense that your code from last week will compile this week. On the other hand, it is currently stable enough that all the major concepts are there and most changes are either syntax or API. So reading up on the changes of last week and some search and replace cover most things. Also, most API changes now are introduced through deprecations. All breaking language changes have an RFC process. The great thing is to see a language while it is still being shaped. Have something you don't like or something that is incredibly clunky? Get involved! The barrier will never be lower. Backwards compatibility is not a thing yet! If the change makes sense and you can muster the resources for it, there is no one holding you back. Code review for pull requests is also awesome, all of my pull requests were accepted on the second or the third try - but for the better! On top of that, it is a really interesting language on it's own right with interesting concepts worth learning.

deleted 12y ago

[deleted]

zimbatm 12y ago

How much cognitive overhead is it to think about ownership all the time once you get used to it ? Coming from a GC-languages background I had a hard time thinking in those terms last time I played with it. I ended up having .clone() littered all over the place :)

pcwalton 12y ago
I find that it's no more mental overhead than it is in C. The nice thing is that the development cycle ends up being faster than C for me because I don't have to spend as much time in front of the debugger.
- deleted 12y ago
  [deleted]
chrismorgan 12y ago
I don’t find that I need to think about it often at all. And very often I can get away with thinking about it less than I should, because if I make a mistake, the compiler will pull me up short. ☺ When writing libraries, you will typically need to think about ownership more frequently than when writing applications, but it’s normally not at all problematic.
aidenn0 12y ago
Writing libraries you need to think about it a lot it really informs the choices for datastructures you make. Other than that, it's considerably easier than other non-managed languages (e.g. C, C++, Pascal)

zwieback 12y ago

I like this a lot, the right level to get an idea of what Rust is about. The last example illustrates that concurrency is complex no matter what language you use - the code ends up reflecting the scaffolding enabling concurrency and the actual work ends up buried inside. That said, I like what I see.

Demagog 12y ago

Frankly, probably the best introduction to Rust is "Rust by example" [1] This is much more in depth + possibility of running code on site. I don't understand why rust site doesn't have links to this project. [1] http://rustbyexample.com/ http://rustbyexample.com/

dbaupp 12y ago
http://doc.rust-lang.org/master/#external-documentation http://doc.rust-lang.org/master/#external-documentation
steveklabnik 12y ago
> This is much more in depth This is Hacker News, so I'll explain it to you this way: this is specifically _not_ in depth. Have you ever done sales? The idea is that you need to figure out if your customer wants to buy as quickly as possible, and if they don't, move on. If they do, _then_ you move into the longform stuff. If your customer isn't going to buy, it wastes both you and their time. The idea of this short introduction is to split you into one of two camps: "I want to know more about Rust," or "ewww." If you're in camp one, heading over to the tutorial or Rust by Example is great!
- AnimalMuppet 12y ago
  Yeah, an "in 30 minutes" article is probably not going to give you "in depth". It's not meant to.

njharman 12y ago

Who is "behind" Rust? A company, consortium, academics, BDFL? http://www.rust-lang.org/ http://www.rust-lang.org/ doesn't have an about page. Didn't see answer listed in the FAQ.

steveklabnik 12y ago
Mozilla is behind most of it. The original creator has already left the project, so we don't have a BDFL. There is a core team, mostly of Mozilla employees. Tilde has been contracted to do the package manager, I have been contracted to do documentation. There's a pretty significant community for a language so young, our IRC channel has ~600 people in it.
bjz_ 12y ago
Mozilla is the big driving force, with a small, dedicated group of developers from Mozilla doing a huge amount of the boring 'grunt work', and also making the hard decisions when it comes to design. The community is a huge driving force though, with lots of great contributions being landed all the time.

blub 12y ago

Out of curiosity I implemented the two examples in C++11. For the number add I used a unique_ptr (although returning by value would be better in every way). For the shared state I used async with a lamba that calls transform and returns the modified vector through a future. This doesn't execute in parallel for each for loop though. I think something like Arc can be coded in C++ too - template wrapper that returns a RAII lock whick unlocks on scope end. I think the only big difference is that some errors in Rust are happening at compile time. In the first case the original buggy code was triggering only a warning in C++. Right now the extra compile-safety of Rust is IMO not worth giving up the other benefits of C++, especially now that C++11 with some extra static checking and good guidelines can go a long way.

steveklabnik 12y ago
Box<T> is roughly equivalent to unique_ptr, and you're correct, returning by value would be better. Rust idiom is to use stack allocation and borrowing wherever possible. > I think the only big difference is that some errors in Rust are happening at compile time. This is true in these examples, except maybe the enforcement of not using a pointer after you've sent it to a task. That said, there are other examples, like iterator invalidation, where Rust is completely memory safe, unlike C++. Furthermore, Rust has significantly less undefined behavior and odd edge cases. These are in C++ for good reason, but they're still there. > with some extra static checking and good guidelines can go a long way. They can go a long way, and that may be enough for you. Big applications continue to have security issues due to problems that Rust would prevent, though: in the last Pwn2Own, all of Firefox's bugs would not have been possible in Rust, for example.
- blub 12y ago
  Thanks for the details. In all honesty I am probably not a target for Rust anyway, I almost never use C++ for systems programming, but rather for (cross-platform) application development. It would seem that neither Rust nor Go serve this area and probably do not intend to do it either.
  - 12y ago

pkulak 12y ago

Wow, is Rust ever changing quickly. I think I read some docs a few months ago and most of this was different. It's gotten better though. All that punctuation for different pointer types was a bit too much. And this way of using mutexes as accessors that unlock automatically when they leave scope is brilliant. I can't wait for Rust to be "done" (and get some kick-ass HTTP support).

steveklabnik 12y ago
Thanks! We have slowly been removing the sigils. As a quick reference: let x = ~5; let y = @5; is now let x = box 5; let y = box(Rc) 5; (though obviously, boxing an integer is silly) > and get some kick-ass HTTP support http://arewewebyet.com/ http://arewewebyet.com/

peaton 12y ago

As someone fairly new to systems programming, I can still see why you'd want to pick a language like Rust over C. But can someone explain to me the difference between Rust and Erlang? They are both system languages, no? Erlang is much more established. But what are the key differences? And I'd ask, "which should I learn?", but that is generally not a great question...

aidenn0 12y ago
"Systems programming" is a broad term, so you are painting in too-broad strokes. I'm not super familiar with Erlang, so I may get some things wrong, but heres a few differences: Erlang prefers GC, wheras Rust tends to eschew it (it's available in a library). Erlang is dynamically typed where rust is statically typed. Erlang is single-assignment where rust uses a somewhat more nuanced lifetime system (though that is still changing). Erlang prefers communication over channels, while rust has immutable types that are safe to share.
- peaton 12y ago
  Are there specific implementation models or areas or systems programming that favor (or have come to use more exclusively) Rust or Erlang?
  - steveklabnik 12y ago
    A significant one is that Rust has no GC, while Erlang does. This can matter if you're trying to build software that's very sensitive to random pauses, or embedded development. Another significant one is that Erlang has been used to make some of the most reliable software ever for the past few decades, and Rust is still pre-1.0.
    - peaton 12y ago
      I don't mean to sounds skeptic when I say this: could you list some of the software (or teams) that use Erlang?