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Maybe the biggest unanswered question about Rust is how much the borrow checking rules can help performance by improving compiler alias information. (There is some use of noalias but it's not very aggressive yet.) If they do by a lot, that changes the calculus for using Rust...

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Patrick Walton

@pcwalton

Aug 13

Like, if the borrow check helps runtime performance, then why wouldn't you use Rust over alternatives? It'd be safer *and* faster.

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Have a newbie write a linked list in rust to see the problem. I'm a fan, but you really have to understand things before you jump in. Obviously we all WANT devs to know their tools before writing a line of code, but other languages can be a bit more forgiving while folks learn.

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Not more difficult to write a correct linked list implementation with Box<T> (singly-linked) or Rc<T> / Weak<T> than malloc in C. Those types exist in C++ as a higher level, easier to use replacement for malloc/new (std::unique_ptr<T>, std::shared_pointer<T>, std::weak_ptr<T>).

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Why Writing a Linked List in (safe) Rust is So Damned Hard

Before I start this post, let me preface it by saying that I’m not an experienced Rustacean by any means. The excellent foks at /r/rust gave a lot of helpful feedback and cleared up some misconcept...

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I'm not sure what that's meant to demonstrate. If you used the wrong types in C++ you would have the same problems but often with runtime memory corruption which you may not notice and which is hard to debug. In C, you're on your own to manage it properly. How is this harder?

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With C you can get a 99% correct solution and feel some level of progress as you learn. This isn't really an option with rust. With C you can work through runtime errors, and with rust you can't even compile. Not all programs need to be 100% correct - especially when learning.

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That's not how memory corruption works in C at all and it doesn't simply manifest as a 'runtime error'. You seem to be talking about a dynamically typed language like Python, not C. It's in no way easier to do this task at a much lower level where you get incomprehensible bugs.

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Rust doesn't enforce that your program is 'correct' and it's not in any way harder to incrementally build a solution. Rust enforces that there isn't memory corruption. A doubly-linked list in Rust and C++ without using raw pointers in either doesn't look that much different.

3:53 PM · Aug 13, 2022Twitter Web App

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You're taking the claim way too far. It is not easier to use manual memory management and deal with the consequences of memory corruption. It is not easier to need to learn how to use ASan, UBSan, etc. just to get partial detection of the issues as they occur at runtime.

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Someone learning C as their first language is going to have a dramatically harder time than someone learning Rust. That includes working their way up to this task as they learn the language and then going through it. If you know C obviously you're quicker in C. Not the point.

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