It's basically doing the same thing that, say, `return true` might do to indicate a function succeeded, but with more explicit types. However, because it uses `Result`, it can be used with the `try`/question mark operator which can be convenient in some situations.

That said, a couple of the examples here feel a bit strange - they're clever things you can do, but they're not necessarily things you often have to do, particularly for a relatively simple task like this. I think the problem with the author's approach is that they can't distinguish between "weird because Rust is weird" and "weird because the LLM generated bad code", because they (understandably) don't have enough experience in what good Rust code looks like.

it is indeed pretty weird. clippy has a lint against this iirc. it's recommended to just create a custom error type, even if its just an empty struct or a single-variant enum

this lets you implement `std::error::Error`, which you really should to make it less painful when you want to erase the type (`std::error::Error` is `dyn`-compatible)

Sometimes you just want a fancy boolean. The advantage is that Result has all the Result APIs and you can compose it with other Results, but otherwise this is just a success bool.

It’s the equivalent of Haskell’s Either, with Option being the equivalent of Maybe. They’re fairly well-defined idioms.