The weird-looking Rust isn’t really Rust being weird, it’s the type telling the truth.
Result<Option<Result<Message, WsError>>, Elapsed>
That’s three independent “not the happy path” channels: timeout, stream closed,
and websocket error.
The nicer version is not a cleverer match. It’s choosing a domain error shape
and converting into it one layer at a time:
let timed = tokio::time::timeout(duration, receiver.next()).await;
let next = timed.map_err(|_| ReceiveError::Timeout)?;
let item = next.ok_or(ReceiveError::Closed)?;
let msg = item.map_err(ReceiveError::WebSocket)?;
The ugly line is what happens when you have not decided where to normalize the
shape yet.
loeg•59m ago
Result<(), ()>
Is pretty weird, though, no? Why would you want a unit value / error type?
tux3•22m ago
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.
MrJohz•22m ago
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.
stingraycharles•12m ago
It’s the equivalent of Haskell’s Either, with Option being the equivalent of Maybe. They’re fairly well-defined idioms.
RobotToaster•48m ago
Was anyone else expecting OpenClaw over gopher protocol?
coqadoodle•8m ago
I was looking forward to retro deep-dive back into the 90s. I just couldn't figure out where the crab fit in.
joshka•1h ago
The nicer version is not a cleverer match. It’s choosing a domain error shape and converting into it one layer at a time:
The ugly line is what happens when you have not decided where to normalize the shape yet.loeg•59m ago
tux3•22m ago
MrJohz•22m ago
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.
stingraycharles•12m ago