I see what you mean, but if that's the problem I'd argue that the weakness is that Rust lacks a shorthand to declare simple enums, not necessarily that it lacks

I see what you mean, but if that's the problem I'd argue that the weakness is that Rust lacks a shorthand to declare simple enums, not necessarily that it lacks keyword parameters. #[derive] soup aside I don't think too bad at the moment though, and I'm not really sure how you could simplify that without introducing too much magic into the language. After all, even with keyword parameters there'll always be plenty of opportunity for one-off enums, if only for situations where more than two choices are possible. Take a typical "seek" function for instance, who can usually be performed relative to the current location, from the start or from the end.