[Ygg2]

> This is a fundamental limitation

Not really. Yeah you need to reach into unsafe to make a doubly linked list that passes borrow checker.

Guess what. You need unsafe implementation to print to console. Doesn't mean printing out is unsafe in Rust.

That's the whole point of safe abstraction.

[josephg]

I love rust, but C does make it a lot easier to make certain kinds of container types. Eg, intrusive lists are trivial in C but very awkward in rust. Even if you use unsafe, rust’s noalias requirement can make a lot of code much harder to implement correctly. I’ve concluded for myself (after a writing a lot of code and a lot of soul searching) that the best way to implement certain data structures is quite different in rust from how you would do the same thing in C. I don’t think this is a bad thing - they’re different languages. Of course the best way to solve a problem in languages X and Y are different.

And safe abstractions mean this stuff usually only matters if you’re implementing new, complex collection types. Like an ECS, b-tree, or Fenwick tree. Most code can just use the standard collection types. (Vec, HashMap, etc). And then you don’t have to think about any of this.

[Ygg2]

> I love rust, but C does make it a lot easier to make certain kinds of container types.

Ok. But making it easier or harder isn't the same as making it impossible.

To quote GP:

> 2) I believe the problem was related to the fact that Rust can't implement a doubly-linked list in safe code.

Rust can implement doubly linked list in safe code. It can. It wraps the unsafe parts in an abstract manner.

[josephg]

> Rust can implement doubly linked list in safe code. It can. It wraps the unsafe parts in an abstract manner.

As far as I know, only with Rc / RefCell. But that has a significant performance cost.

Am I wrong? I'd love to see an example / benchmarks.