That's easier said than done, and it's not obvious how to do it with types. Consider a non-blocking read. What the caller does depends on whether the read ret

That's easier said than done, and it's not obvious how to do it with types. Consider a non-blocking read. What the caller does depends on whether the read returns a value or "no data available". If the type of the object returned depends on whether there was a value, you just replaced a null check with a type check. You can avoid that check with a caller with multiple return points and have the callee pick between them. Exceptions are the most obvious way to do that. However, exceptions happen immediately, while type/null checks can be done later.