Comment by bigstrat2003 3 days ago
They are a good idea. They solve the problem that you don't know where an exception is coming from (the "invisible control flow" complaint), and let the compiler help you to avoid mistakes when refactoring. There is zero valid reason to hate on checked exceptions.
When you use lambdas you lose control over when and how often your code gets executed. Since checked exceptions are very often thrown by code that has side effects, I'd consider the friction to be a feature.
> collecting all the thrown exceptions in a separate loop
It's really not comfortable to do so in Java since there is no standard `Either` type, but this is also doable with a custom collector.
> Since checked exceptions are very often thrown by code that has side effects, I'd consider the friction to be a feature.
This is true, but I think that it’s partly true because checked exceptions are cumbersome here. In my ideal world, the majority of functions would throw exceptions, testing cases that today are either missed or thrown as unchecked exceptions.
The only problem with them is that they don’t work well with lambdas (and related features like Stream). If you need to call a method that throws a checked exception inside of a Stream, there’s no good way to pass it up other than re-throwing it as unchecked or some other hack (like collecting all the thrown exceptions in a separate loop).
A different implementation of lambdas that allow for generic exceptions would probably solve it, but then that introduces other issues with the type system.
My other complaint is that the standard library didn’t have enough pre-made exceptions to cover common usecases.