What if I just copied the Svelte compiler, written in TypeScript, changed all of the file extensions from .ts to .rs, and fixed all the bugs? It'd be a slog, sure, but at the end of the day I'd have a compiler that was very nearly the same, but presumably more performant.
This attempt I gave a real try, spending maybe three nights just chugging away. What I got was just more and more errors, which was fairly disheartening. I also realized just how different Rust is, and that a 1-to-1 rewrite would result in something that wouldn't be as ideal as it could be. For example, take this very simple TypeScript class:
class Node extends BaseNode {
name: String? = null,
children: Node[] = [],
}
The equivalent Rust struct might look like:
struct Node {
base: BaseNode,
name: Option<String>,
children: Vec<Node>
}
I don't think that's great. What fields belong on Node? Which belong on BaseNode? Plus TypeScript's got a garbage collector, so for parity any T should probably be wrapped in an Rc<T>. Plus everything's mutable, so we'd want to wrap that in a RefCell<T>.
struct Node {
base: BaseNode,
name: Option<String>,
children: Vec<Rc<RefCell<Node>>>
}
While probably fine, this just looks it'd like a pain to work with. I think we can do better. These nodes don't really reference each other, so we don't actually need an Rc, and without that we wouldn't need a RefCell. Also I'm up to 1337 errors, so I'm pretty happy ending this attempt here.