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It isn't "don't know how to write low level code" in my view, it is more "don't think it is productive to reimplementat basic data structures over and over agai

It isn't "don't know how to write low level code" in my view, it is more "don't think it is productive to reimplementat basic data structures over and over again". All the stuff you're saying you can't write in idiomatic rust is stuff that has already been written and battle tested in libraries, which are perfectly idiomatic to use. I don't need to write my own linked list and binary tree implementations over and over again. I did that in school, I can go check the code in the libraries I'm using to confirm it makes sense to me, and then just use the library and go about doing what I'm actually trying to do.

Jensson 5y ago
> All the stuff you're saying you can't write in idiomatic rust is stuff that has already been written and battle tested in libraries It is fine for you to not be able to think of any scenarios where the battle tested standard libraries wouldn't be sufficient. But as someone who wrote low level libraries running in production at Google that doesn't apply to me, for me knowing what it would take to eek out performance in Rust compared to C++ is absolutely necessary and given how hostile people are my guess is that the Rust wouldn't look pretty so there is no reason for me to even try to pick up Rust. And you can't say that I am not your intended user, if you chase away people like me from the rust ecosystem then there is no way that Rust can replace C++ in any reasonable timeframe. What I'd like to see is a lot of examples and such showing how to write very complex things using unsafe rust. Because without that there is no way rust can compete, there are already plenty of people who know how to write highly performant code using unsafe C++.
- follower 5y ago
  I just saw this and thought of you, "Learn Rust the Dangerous Way": http://cliffle.com/p/dangerust/ http://cliffle.com/p/dangerust/ "LRtDW is a series of articles putting Rust features in context for low-level C programmers [...] the sort of people who work on firmware, game engines, OS kernels, and the like. Basically, people like me." Also, it seems like the author probably also wrote some low level libraries at Google... :)
- sanderjd 5y ago
  You are definitely (one of) the intended audiences of rust, just to dispense with any confusion there. I don't at all think that there are not "any scenarios where the battle tested standard libraries wouldn't be sufficient". I spent a number of words on exactly that in another comment below. My point in that comment was that the use case I don't believe actually exists in production code is "I'm just gonna knock out a simple bespoke implementation of a binary tree". I'm not saying people don't do that, but they shouldn't. If what you need is simple, there is a good library for it. And if the library for it is not sufficient, then it is important enough to invest time into writing a good implementation. Maybe here's a way to put it: simple bespoke implementations of linked data structures are easy in both c++ and rust using ref counting, slightly better but low-investment implementations are still pretty easy in c++ but are not really possible in rust, and really good implementations are possible in both languages if the investment is worthwhile for the use case. It is true that you would have to learn how to write such a thing in rust and that it would be non trivial to do so, but that is just part of learning a new programming language to an expert level. I think one misconception in here is that the rust "wouldn't look so pretty". You could do a line for line port of your c++ code using raw pointers and declare it safe, and the two implementations would have similar aesthetics. If your c++ implementation were memory safe to begin with, your rust implementation will be as well. The same process of thinking through the invariants and implementing them correctly is necessary in both languages. I think the pushback you get that you find off-putting is against the sometimes expressed idea that it is a big knock against rust that you can't do linked data structures with zero cost abstractions in safe rust. This is why people say either "yeah but you can do minimal cost implementations in safe rust and zero cost implementations in unsafe rust". The pushback is against the idea that this isn't a good enough solution. But it totally is, it's certainly no worse than the situation in c++ where the division between a safe and unsafe subset of the language does not exist. Unsafe rust is no different than generic c++ code. To your last point, there's a great book / reference called The Rustonomicon that is all about writing unsafe rust code well.
  - follower 5y ago
    A link to the aforementioned Rustonomicon: https://doc.rust-lang.org/nomicon/ https://doc.rust-lang.org/nomicon/ (I seem to recall a comment that it hasn't yet been fully updated for recent versions.)

Jensson 5y ago

> All the stuff you're saying you can't write in idiomatic rust is stuff that has already been written and battle tested in libraries It is fine for you to not be able to think of any scenarios where the battle tested standard libraries wouldn't be sufficient. But as someone who wrote low level libraries running in production at Google that doesn't apply to me, for me knowing what it would take to eek out performance in Rust compared to C++ is absolutely necessary and given how hostile people are my guess is that the Rust wouldn't look pretty so there is no reason for me to even try to pick up Rust. And you can't say that I am not your intended user, if you chase away people like me from the rust ecosystem then there is no way that Rust can replace C++ in any reasonable timeframe. What I'd like to see is a lot of examples and such showing how to write very complex things using unsafe rust. Because without that there is no way rust can compete, there are already plenty of people who know how to write highly performant code using unsafe C++.

follower 5y ago
I just saw this and thought of you, "Learn Rust the Dangerous Way": http://cliffle.com/p/dangerust/ http://cliffle.com/p/dangerust/ "LRtDW is a series of articles putting Rust features in context for low-level C programmers [...] the sort of people who work on firmware, game engines, OS kernels, and the like. Basically, people like me." Also, it seems like the author probably also wrote some low level libraries at Google... :)
sanderjd 5y ago
You are definitely (one of) the intended audiences of rust, just to dispense with any confusion there. I don't at all think that there are not "any scenarios where the battle tested standard libraries wouldn't be sufficient". I spent a number of words on exactly that in another comment below. My point in that comment was that the use case I don't believe actually exists in production code is "I'm just gonna knock out a simple bespoke implementation of a binary tree". I'm not saying people don't do that, but they shouldn't. If what you need is simple, there is a good library for it. And if the library for it is not sufficient, then it is important enough to invest time into writing a good implementation. Maybe here's a way to put it: simple bespoke implementations of linked data structures are easy in both c++ and rust using ref counting, slightly better but low-investment implementations are still pretty easy in c++ but are not really possible in rust, and really good implementations are possible in both languages if the investment is worthwhile for the use case. It is true that you would have to learn how to write such a thing in rust and that it would be non trivial to do so, but that is just part of learning a new programming language to an expert level. I think one misconception in here is that the rust "wouldn't look so pretty". You could do a line for line port of your c++ code using raw pointers and declare it safe, and the two implementations would have similar aesthetics. If your c++ implementation were memory safe to begin with, your rust implementation will be as well. The same process of thinking through the invariants and implementing them correctly is necessary in both languages. I think the pushback you get that you find off-putting is against the sometimes expressed idea that it is a big knock against rust that you can't do linked data structures with zero cost abstractions in safe rust. This is why people say either "yeah but you can do minimal cost implementations in safe rust and zero cost implementations in unsafe rust". The pushback is against the idea that this isn't a good enough solution. But it totally is, it's certainly no worse than the situation in c++ where the division between a safe and unsafe subset of the language does not exist. Unsafe rust is no different than generic c++ code. To your last point, there's a great book / reference called The Rustonomicon that is all about writing unsafe rust code well.
- follower 5y ago
  A link to the aforementioned Rustonomicon: https://doc.rust-lang.org/nomicon/ https://doc.rust-lang.org/nomicon/ (I seem to recall a comment that it hasn't yet been fully updated for recent versions.)