[sanderjd]

> The whole point of rusts type system is to try to ensure safe memory usage.

It isn't though. The whole trait system is unnecessary for this goal, yet it exists. ADTs are unnecessary to this goal, yet they exist. And many of us like those aspects of the type system even more than those that exist to ensure safe memory usage.

[dartos]

It is the first and foremost goal of every language choice in rust.

I think traits muddy that goal, personally, but their usefulness outweighs the cost (Box<dyn ATrait>)

I should’ve probably said “the whole point of rusts type system, other than providing types and generics to the language”

But I thought that went without saying

[sanderjd]

> It is the first and foremost goal of every language choice in rust.

It ... just ... isn't, though.

I mean, I get what you're saying, it's certainly foundational, Rust would look incredibly different if it weren't for that goal. But it just isn't the case that it is "the first and foremost goal of every language choice in rust".

I followed the language discussions in the pre-1.0 days, and tons of them were about making it easier and more ergonomic to create correct-if-it-compiles code, very often in ways that had zero overlap with safe memory usage.

Traits don't "muddy that goal", they are an important feature of the language in and of themselves. Same thing with the way enums work (as arithmetic data types), along with using Option and Result for error handling, rather than exceptions. Same thing with RAII for tying the lifecycle of other resources to the lifecycle of values.

The memory safety features interact with all these other features, for sure, and that must be taken into account. But there are many features in the language that exist because they were believed to be useful on their own terms, not in subservience to safe memory usage.

And it's not just about "providing types and generics to the language", it's a whole suite of functionality targeted at static correctness and ergonomics. The ownership/lifetime/borrowing system is only one (important!) capability within that suite.