[swift-evolution] [Pitch] Introducing the "Unwrap or Die" operator to the standard library

Jacob Williams ponyboy47 at gmail.com
Wed Jun 28 10:52:06 CDT 2017

I feel that the !! operator would be necessary for indicating that if this fails then something went horribly wrong somewhere and we should throw the fatalError. This allows the inclusion of optimizations using -Ounchecked and is clear that this is an operation that could result in a runtime error just like force unwrapping.

If we want code clarity and uniformity, then I think !! Is much better than ?? because it goes right along with the single ! Used for force unwrapping. However, this does depend on if the operator would be returning some kind of error that would cause the program to exit.

I think the ?? operator should not cause a program to exit early. It goes against optional unwrapping principles. I think code could get very confusing if some ? would return nil/a default value, and others would be causing your program to crash and exit. The ? operators should always be classified as safe operations.

> On Jun 28, 2017, at 9:41 AM, Ben Cohen via swift-evolution <swift-evolution at swift.org> wrote:
>> On Jun 28, 2017, at 8:27 AM, David Hart via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> Count me in as a strong proponent of ?? () -> Never. We don't need to burden the language with an extra operator just for that.
> You could say the same about ??
> The concern that an additional operator (and one that, IMO, fits well into existing patterns) is so burdensome seems way overweighted in this discussion IMO. 
> Adding the operator, and encouraging its use, will help foster better understanding of optionals and legitimate use of force-unwrapping in a way that I don’t think `?? fatalError` could.
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