[munificent]

> Even in an OOP language you probably want `UUID.from(string): Maybe<UUID>`, not `new UUID(string)` that throws.

One way to think about exceptions is that they are a pattern matching feature that privileges one arm of the sum type with regards to control flow and the type system (with both pros and cons to that choice). In that sense, every constructor is `UUID.from(string): MaybeWithThrownNone<UUID>`.

[9rx]

The best way to think about exceptions is to consider the term literally (as in: unusual; not typical) while remembering that programmers have an incredibly overinflated sense of ability.

In other words, exceptions are for cases where the programmer screwed up. While programmers screwing up isn't unusual at all, programmers like to think that they don't make mistakes, and thus in their eye it is unusual. That is what sets it apart from environmental failures, which are par for the course.

To put it another way, it is for signalling at runtime what would have been a compiler error if you had a more advanced compiler.

[SAI_Peregrinus]

Unfortunately many languages treat exceptions as a primary control flow mechanism. That's part of why Rust calls its exceptions "panics" and provides the "panic=abort" compile-time option which aborts the program instead of unwinding the stack with the possibility of catching the unwind. As a library author you can never guarantee that `catch_unwind` will ever get used, so its main purpose of preventing unwinding across an FFI boundary is all it tends to get used for.

[9rx]

> Unfortunately many languages

Just Java (and Javascript by extension, as it was trying to copy Java at the time), really. You do have a point that Java programmers have infected other languages with their bad habits. For example, Ruby was staunchly in the "return errors as values and leave exception handling for exceptions" before Rails started attracting Java developers, but these days all bets are off. But the "purists" don't advocate for it.

[SAI_Peregrinus]

Python as well. E.g. FileNotFoundError is an exception instead of a returned value.