It's not subtle in that it's not opaque to the programmer that it's just a "regular" sum type It's not important in that it doesn't change what the programmer

It's not subtle in that it's not opaque to the programmer that it's just a "regular" sum type It's not important in that it doesn't change what the programmer can do with it, it just changes the syntax used. Return an error: return Err(...) vs. throw ... Propagate error to caller: ? vs. nothing Store/modify/nest/pass: Without try/catch/throw construct vs. WITH try/catch/throw construct. The much more important difference is between bounded vs. unbounded error types. Rust falls in the former camp and inherits all the problems (and benefits) that come with it.