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Comment by nickbauman | Hacker News Reader

Yeah the borrow checker is an interesting solution to a problem I don't have with a managed language. It's the main "safety" feature people coming to rust are introduced. I'm in agreement about Rust here with a lot: "one does not let one's friends skip leg day" there's a lot more to good language design than memory management. Is it worth it?

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One of the things I like about non-managed languages is the ability to have true destructors. Releasing resources is awkward at best in Java, et al.

Note that you can have linear types (which is what gives you what you're talking about) in managed languages. You can have them as an extension in Haskell for exemple.

Rust is the only mainstream-ish language to really use them, though.

Rust uses a mixture of affine and ... "regular"? types. My understanding is that affine is a looser version of linear because the type doesn't have to be consumed.

You can have dtors in non-affine types (types that implement the Copy trait) in Rust as well. I'm really only talking about C++ style destructors. Those don't require linear or affine types. But, I agree, that in a managed language, having a linear type is one way to get predictable destructors to run.

Strangely, Swift has deinit{} for its class types (ref-counted), but not for its struct types (value types).

You cannot implement Drop for a Copy type.

Fair enough! I never wanted to implement Drop on a Copy type, but I assumed you could.

> "one does not let one's friends skip leg day"

That is such a silly meme. It's silly because it suggests that Rust is a one-trick pony, or that it only focuses on memory safety, which isn't true in the least.

Besides, the borrow checker has at least one other major upside: Show me another mainstream language in which safe and efficient shared-memory concurrency and parallelism is as easy as in Rust.

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