[rsanek]

If you want to force people to handle the above 3 cases, couldn't you just throw separate checked exceptions (eg in Java)? In that case the compiler does care about it. You can still catch and ignore but that imo is not a limitation of the language's expressiveness.

[cmrdporcupine]

Checked exceptions would have been an ok idea if it weren't for the fact that at least when I was writing Java last (almost 10 years ago) they were expressly discouraged in most code bases. Partially because people just get in the lazy habit of catch and rethrow RuntimeException, or catch and log, etc. when confronted with them. Partially because the JDK itself abused them in the early days for things people had no hope of handling properly.

They also tend to defer handling out into places where the context isn't always there.

The trend in language design does seem to be more broadly away from exceptions for this kind of thing and into generic pattern matching and status result types.

[mrkeen]

> Checked exceptions would have been an ok idea

> Partially because people just get in the lazy habit of catch and rethrow RuntimeException, or catch and log, etc. when confronted with them.

After quite a while of thinking this way, I came to the conclusion that:

95% of the time, there's no way to 'handle' an error in a 'make it right' sense. Disk write failed? REST request failed? DNS lookup? There usually isn't an alternative to logging/rethrowing.

When there is a way to handle an error (usually by retrying?), it's top level anyway.

Furthermore, IO is the stuff that can just 'go wrong' regardless of how good the programmer is, and IO tends to sit at the bottom in most Java programs. This means every method call is prone to IOExceptions.

[cmrdporcupine]

Yes, after a few years of Java we all end up there. Frankly it's a good argument for the Erlang "Let It Crash" philosophy.

https://verraes.net/2014/12/erlang-let-it-crash/

If IOException on a read is truly happening, and it isn't just a case of a missing file, there are serious issues that aren't going to be fixed with a catch-and-log, or be able to be handled further up the call stack.

[nicoburns]

One benefit I've found with error-enums is just being aware of all the possible errors that can occur. You're right: 95% of the time you can't do anything except log/retry. But that 5% of the time become runtime bugs which are a massive pain. It's really nice when that is automatically surfaced for you at development time.

[frenchy]

Note that checked exceptions are essentially the same thing as returning a tagged union, from a theoretical perspective at least.

They're not popular in Java though, because the ergonomics is a lot worse than working with a Result type.