I know, but in Rust's case it was more straightforward to call it Ok/Err since that was the majority use-case. Personally I prefer Either, since then you have a

I know, but in Rust's case it was more straightforward to call it Ok/Err since that was the majority use-case. Personally I prefer Either, since then you have a more generic sum type, just like the tuple type is a more generic product type (and if I'm using the terminology correctly).