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Rust only limits you from writing nonsense code. Seriously that's what the compiler is doing, and that's what people are complaining about. "Why won't this lang

Rust only limits you from writing nonsense code. Seriously that's what the compiler is doing, and that's what people are complaining about. "Why won't this language let me write bad code!". I get it it's hard to learn at first, but, it sounds a little silly to people who have spent the time learning the language... Believe it or not industry has and is continuing to adopt rust. Microsoft, AWS, government agencys in Europe, the Linux kernel itself (the only other language allowed there is C - think about it). It's really not all hype, people like it because it solves a class of problems from never happening while still performing very well. I invite you to join the community and learn it. It's a lot of fun once you get proficient with it.

Georgelemental 4y ago
> Rust only limits you from writing nonsense code This is the ideal, but not always the reality. The Rust borrow checker isn't perfect, so sometimes it rejects code that should work perfectly fine. Hopefully as the language matures (Polonius, GATs, HRTBs…) these cases will become rarer.
- shric 4y ago
  Is there a simple example you can point to of rejected code that should work perfectly fine?
  - foldr 4y ago
    A doubly linked list is a classic example. To implement this in Rust you need to use unsafe code. Come to think of it, an even simpler example is a mutable iterator for a typical data structure. Such iterators usually require 'unsafe' code to implement, even though they are perfectly safe to use. https://stackoverflow.com/questions/63437935/in-rust-how-do-i-create-a-mutable-iterator https://stackoverflow.com/questions/63437935/in-rust-how-do-...
    - bombela 4y ago
      Yes, it has limits. And unsafe let you C++ your way out of it. At least, little code requires unsafe and thar makes it easier to audit.
    - crabbygrabby 4y ago
      Unsafe in rust means you are skirting guarantees given by the language. It doesn't mean the code will blow up when run. It's just an explicit way to tell the compiler you are operating at your own risk. So when you do get UB from using unsafe you look at those places rather then your entire code base... A lot of people don't seem to realize how easy it is to get UB in other languages. The C spec for example claimed not having a trailing newline at the end of a file was UB... I also don't think this was an example of code that should compile but doesn't. Rusts' ownership rules make this task hard, but there are lots of people using doubly linked lists in rust... Yes they used unsafe code to do it, and yes it does compile . The question was show us a case where the borrow checker was wrong.
      - foldr 4y ago
        >Unsafe in rust means you are skirting guarantees given by the language. It doesn't mean the code will blow up when run. It's just an explicit way to tell the compiler you are operating at your own risk. I'm fully aware of this. That's why I put 'unsafe' in quotes. However, it's surely fair to point out that you can't implement doubly linked lists or mutable iterators in Rust without giving up Rust's usual guarantee of memory safety. If this guarantee is not actually that big of a deal, as you appear to be suggesting, then why all the hype about it from Rust advocates? >The question was show us a case where the borrow checker was wrong. No, that was not the question. OP just asked for 'rejected code that should work perfectly fine'. There are of course loads of examples of such code. Perhaps the simplest is the case of mutable iterators that I mentioned. A correctly implemented mutable iterator is perfectly safe, but rejected by Rust's borrow checker unless certain parts of the implementation are marked unsafe.
        mumblingdrunk 4y ago
        It seems you are slightly misunderstanding the point of 'unsafe' as a concept. And no, memory safety is a huge deal, it is just that the borrow checker cannot verify the soundness of certain code, meaning you have to provide the guarantees normally given to you outside 'unsafe' blocks. Yes, this means that a few data structures require 'unsafe', but you should be creating safe wrappers around these structures; 'unsafe' won't propagate up your code and poison everything.
wheelerof4te 4y ago
"I invite you to join the community and learn it. It's a lot of fun once you get proficient with it." I will if the Rust community agrees on a lighter, less complex language core. "Microsoft, AWS, government agencys in Europe, the Linux kernel itself (the only other language allowed there is C - think about it)." Again, they are using only a subset of the language. Linus allowed it in the kernel once devs agreed only to use the Rust core features. They even had to make a new memory allocator, IIRC.
- steveklabnik 4y ago
  You’re confusing standard library naming. Rust has a layered standard library, “core” and then “std” on top of it. They’re using the core library, because that’s what you do in an OS context. But as far as I know they don’t restrict any language features. They also didn’t have to write a new allocator; they did extend the interface of the “alloc” library (which sits between core and std) which was then also accepted upstream.
  - crabbygrabby 4y ago
    Thank you Steve. There is so much misinformation surrounding rust it's unreal... It's also kind of normal to you know tweak a language so it integrates with an OS better... Even if they did change their allocator, who cares?
  - wheelerof4te 4y ago
    So, what software can you make without relying on "std" library? I think that a lot of complexity in Rust comes from many different ways to handle memory. You have your Arcs, Boxes, Cells, etc. Then you have a core "alloc" library. Maybe if everyone agreed on a single reliable method to handle heap memory (since using stack is easy), Rust wouldn't be so hard to use. The syntax also could be improved. Seeing <Box(T)> or whatever nested three or more levels deep hurts my eyes.
    - mumblingdrunk 4y ago
      You don't have access to the C standard library in the Linux kernel either, so what is your point? Ime., the core library of Rust is much nicer to work with than the absolute bare bones landscape that is C when compiled with -nostd. Boxes, cells, arcs, etc. exist for different purposes and if you'd take two hours to actually read about them and their uses, you'd understand why they exist.
nbittich 4y ago
The problem with rust is its community. A bunch of groupies acting worst than kpop stans on twitter. If you don't make abstraction and write spaghetti code, or if you clone everything, then yeah rust work-ish.

Georgelemental 4y ago

> Rust only limits you from writing nonsense code This is the ideal, but not always the reality. The Rust borrow checker isn't perfect, so sometimes it rejects code that should work perfectly fine. Hopefully as the language matures (Polonius, GATs, HRTBs…) these cases will become rarer.

shric 4y ago
Is there a simple example you can point to of rejected code that should work perfectly fine?
- foldr 4y ago
  A doubly linked list is a classic example. To implement this in Rust you need to use unsafe code. Come to think of it, an even simpler example is a mutable iterator for a typical data structure. Such iterators usually require 'unsafe' code to implement, even though they are perfectly safe to use. https://stackoverflow.com/questions/63437935/in-rust-how-do-i-create-a-mutable-iterator https://stackoverflow.com/questions/63437935/in-rust-how-do-...
  - bombela 4y ago
    Yes, it has limits. And unsafe let you C++ your way out of it. At least, little code requires unsafe and thar makes it easier to audit.
  - crabbygrabby 4y ago
    Unsafe in rust means you are skirting guarantees given by the language. It doesn't mean the code will blow up when run. It's just an explicit way to tell the compiler you are operating at your own risk. So when you do get UB from using unsafe you look at those places rather then your entire code base... A lot of people don't seem to realize how easy it is to get UB in other languages. The C spec for example claimed not having a trailing newline at the end of a file was UB... I also don't think this was an example of code that should compile but doesn't. Rusts' ownership rules make this task hard, but there are lots of people using doubly linked lists in rust... Yes they used unsafe code to do it, and yes it does compile . The question was show us a case where the borrow checker was wrong.
    - foldr 4y ago
      >Unsafe in rust means you are skirting guarantees given by the language. It doesn't mean the code will blow up when run. It's just an explicit way to tell the compiler you are operating at your own risk. I'm fully aware of this. That's why I put 'unsafe' in quotes. However, it's surely fair to point out that you can't implement doubly linked lists or mutable iterators in Rust without giving up Rust's usual guarantee of memory safety. If this guarantee is not actually that big of a deal, as you appear to be suggesting, then why all the hype about it from Rust advocates? >The question was show us a case where the borrow checker was wrong. No, that was not the question. OP just asked for 'rejected code that should work perfectly fine'. There are of course loads of examples of such code. Perhaps the simplest is the case of mutable iterators that I mentioned. A correctly implemented mutable iterator is perfectly safe, but rejected by Rust's borrow checker unless certain parts of the implementation are marked unsafe.
      - mumblingdrunk 4y ago
        It seems you are slightly misunderstanding the point of 'unsafe' as a concept. And no, memory safety is a huge deal, it is just that the borrow checker cannot verify the soundness of certain code, meaning you have to provide the guarantees normally given to you outside 'unsafe' blocks. Yes, this means that a few data structures require 'unsafe', but you should be creating safe wrappers around these structures; 'unsafe' won't propagate up your code and poison everything.

wheelerof4te 4y ago

"I invite you to join the community and learn it. It's a lot of fun once you get proficient with it." I will if the Rust community agrees on a lighter, less complex language core. "Microsoft, AWS, government agencys in Europe, the Linux kernel itself (the only other language allowed there is C - think about it)." Again, they are using only a subset of the language. Linus allowed it in the kernel once devs agreed only to use the Rust core features. They even had to make a new memory allocator, IIRC.

steveklabnik 4y ago
You’re confusing standard library naming. Rust has a layered standard library, “core” and then “std” on top of it. They’re using the core library, because that’s what you do in an OS context. But as far as I know they don’t restrict any language features. They also didn’t have to write a new allocator; they did extend the interface of the “alloc” library (which sits between core and std) which was then also accepted upstream.
- crabbygrabby 4y ago
  Thank you Steve. There is so much misinformation surrounding rust it's unreal... It's also kind of normal to you know tweak a language so it integrates with an OS better... Even if they did change their allocator, who cares?
- wheelerof4te 4y ago
  So, what software can you make without relying on "std" library? I think that a lot of complexity in Rust comes from many different ways to handle memory. You have your Arcs, Boxes, Cells, etc. Then you have a core "alloc" library. Maybe if everyone agreed on a single reliable method to handle heap memory (since using stack is easy), Rust wouldn't be so hard to use. The syntax also could be improved. Seeing <Box(T)> or whatever nested three or more levels deep hurts my eyes.
  - mumblingdrunk 4y ago
    You don't have access to the C standard library in the Linux kernel either, so what is your point? Ime., the core library of Rust is much nicer to work with than the absolute bare bones landscape that is C when compiled with -nostd. Boxes, cells, arcs, etc. exist for different purposes and if you'd take two hours to actually read about them and their uses, you'd understand why they exist.

nbittich 4y ago

The problem with rust is its community. A bunch of groupies acting worst than kpop stans on twitter. If you don't make abstraction and write spaghetti code, or if you clone everything, then yeah rust work-ish.