This RFC presents an attempt to unify parts of the syntatical styles between exceptions vs results based error handling techniques. The two styles can be implemented in a somewhat similar fashion under the covers, but do offer quite different ergonomics. In an ideal world we can take the best from both styles as fits a given situation.
The core idea of this RFC is to present a gradual typing like system for enhancing error typing. This provides attempts to provide a best of all worlds and let folks decide how strictly they want to track their error types in a given set of code.
Another idea is to provide a seamless integration from full exceptions to enum based error codes. While it provides nice ergonomics, this may not be desirable at an implementation level though.