Declaring only some of the things that might go wrong, which is the case with checked exceptions, does not solve the problem you described and only makes it mor

Declaring only some of the things that might go wrong, which is the case with checked exceptions, does not solve the problem you described and only makes it more difficult to write code. If every kind of exception was checked, then every method in Java, including constructors, would need to declare that it throws RuntimeException and IOException and NullPointerException and NoClassDefFoundError and InterruptedException because those things could happen in any method. So we settle for declaring the type a function is expected to return, with the understanding that if something exceptional occurs a magical thing called an Exception will be thrown and it's not handled the same way as a return value. This lets us get our jobs done. It's engineering, not science. When you solve the halting problem we can talk about formalizing every possible failure state as a return value. Until then we will get on with our lives.