Pitching Optional Throws in Swift

[Tino]

It's not that easy to search, and I have the feeling I did not find the thread I remembered... but for reference:

Throws? and throws!

I really like swift’s error handling system overall. It strikes a good balance between safety and usability. There are some cases where it would be nice to throw errors, but errors are rarely expected in most use cases, so the overhead of ‘try’, etc… would make things unusable. Thus fatalError or optionals are used instead. For example, operators like ‘+’ could never throw because adding ’try’ everywhere would make arithmetic unbearable. But in a few cases it would make my algorithm much clean…

throws!

For context, I just read this thread (that happened before I joined) which discusses the idea of having a variant of arithmetic which can throw on overflow: https://lists.swift.org/pipermail/swift-evolution/2015-December/000292.html I wonder if having a variant of ‘throws’ might allow this... ‘throws!’ would act exactly like throws, but it could be called without ‘try’ (resulting in a crash if it tries to throw). Basically, any statement calling a function/operation with throws! would have …