That seems to me to be an implementation detail though. There's no real reason you can't have a compiler that converts exception-throwing-code into error-code-

That seems to me to be an implementation detail though. There's no real reason you can't have a compiler that converts exception-throwing-code into error-code-returning-code. That'd basically cost you the performance of a couple if-statements per function call return, which doesn't seem too excessive to me. Of course most languages don't implement exceptions this way and I'm sure there's a good reason for it but you can still choose -- as a language implementor -- to have cheap exceptions.