> structs in Swift are the same as structs in Rust, and a class is a heap-allocated reference counted box, like an Arc<Box<T>>.

Yeah, and by representing the differences this way, Rust allows you to easily decide whether an object is used directly or is wrapped in a rc box when its used, instead of when it's defined, often not by you, and when you change your mind you don't need to change all methods or functions than mutates it and all their call sites.

> Result builders are a language feature and not part of SwiftUI

I admit that this is the first time I see the term result builders. This is never mentioned in any SwiftUI documentation I've seen, so I guess I should extend my complaint to include quality of docs :p. Whatever this is called you seem to agree that the syntax is hacked and it can get hard to understand what something means