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Comment by pcwalton | Hacker News Reader

I actually used to agree that Rust generally wasn't good for high-level application code, but working with Bevy has made me change that opinion for certain domains. I simply haven't seen a system that makes automatically parallelizing all application logic (game logic, in this case) feasible, other than Bevy and other Rust-based systems. The trick is that the borrow check gives the scheduler enough information to automatically safely determine which systems can run in parallel, and that's very powerful. It's not that you couldn't do this in C# or whatever--it's that you won't without a system that helps express your intent and enforces that those declarations are up to date.

For applications that don't need high performance for the CPU code and aren't systems code, sure, Rust may not be a good choice. I'm not writing the server-side code for low traffic Web sites in Rust either.

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Just so we're clear, your reference points for "good for high-level application code" are systems code and game engines? :)

Games themselves, not game engines. Systems code, game engines, and games.

This isn't meant to be an exhaustive list--it's just the domains I have experience with that Rust was a good fit for. Lest it seem like I'm saying Rust is a good fit for everything I've done, I also worked on Firefox where the UI was JavaScript, and I wouldn't hurry to rewrite that code in Rust. Nor would I want the throwaway stuff I write in Python or Ruby to be Rust.

I'm just saying, games are exactly one of the things I would assume Rust would be a natural fit for. :)

>Rust would be a natural fit for

Did you leave out a "not" here?

No, I don't think so? I would have predicted games as a sweet spot for Rust. Most significant game projects are done in C++, and I look at Rust as basically obsoleting C++.

OK. Thanks.

My guess was that since almost no one will pay more for a game's having fewer security vulns, there is less benefit to incurring the expense of Rust (takes longer to learn, development speed is slightly less)

Its not just vulnerabilities. In theory you should also get more stability.

For example I like to play Civ with a friend, but stopped because about once every 30 minutes one of us would have their game crash. If it was written in Rust, I assume it might be more stable.

Thanks. Another consideration that favors Rust, at least for game engines, is https://news.ycombinator.com/item?id=41793725

When we talk about Rust being a reasonable choice for things like (say) a CRUD app, memory safety is already table stakes; every mainstream high-level language is memory-safe. Why would you ever pick Rust over Java? The answer to that question will be an even better answer to why you'd write a game in Rust.

Java may be memory safe but it is not data race safe (unlike Rust, the compiler does not enforce cross-thread synchronization). So there is still a safety-related reason to use Rust over Java.

That said, I don't really think Rust is a good choice for CRUD apps, because development velocity is more important than performance and they probably don't need to be multithreaded anyway.

But Rust would have been great for a lot of "systems" stuff that was historically written in Java, like Flink or Hadoop for example.

I feel like I've had this debate many, many times, and it always ends in the same place: I'm willing to concede that there are a subset of correctness/reliability bugs that Rust's error handling and type system mitigate, but not that any of those bugs are material to security, which is what most people are talking about when the discussion turns to memory safety. And, of course, Rust admits concurrency bugs too! We just ran into a huge one.

I didn’t think we were having a debate. You insinuated that Rust isn’t ideal for CRUD apps, and I agreed with you.

"Debate" was too confrontational a word, sorry about that.

Rust's value proposition has nothing to do with security vulnerabilities, except that security vulnerabilities are a type of bug.

The point of Rust is to be a language that competes in the same niche as C++ but makes it much more difficult to write large classes of bug, much broader than just "security vulns".

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