[xmcqdpt2]

C++/Rust are different because exceptions in those languages are expensive and culturally counter indicated.

For the runtime-hosted languages the author is talking about (JVM, CLR, Python etc.), optionally throwing an exception is much cheaper than constantly creating and unwrapping Result objects. Your example is a perfect case where one would prefer to throw: say you have a parser that parses your file and the parser is expensive because the files are large. You are better off throwing out of your parsing iteration then doing a Result.map in your hot loop. (However you might want to wrap the top level of the parser in a Result and return that.)