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

[Max Moiseev]

> On Jun 27, 2017, at 10:38 AM, Xiaodi Wu via swift-evolution <swift-evolution at swift.org> wrote:
> 
> As you write, this operator becomes sugar for “?? fatalError()” once Never becomes a true bottom type.
> 
> In the meantime, can’t the same thing be accomplished by overloading fatalError so it’s a generic function that returns a discardable result of type T, which in turn calls the Never-returning overload?

I like this idea more than adding an extra operator, but overloading fatalError won’t work now because of https://github.com/apple/swift/blob/master/stdlib/public/core/Optional.swift#L668 <https://github.com/apple/swift/blob/master/stdlib/public/core/Optional.swift#L668>




> On Tue, Jun 27, 2017 at 12:25 Erica Sadun via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> Using an operator to provide feedback on the context of a failed unwrap has become a commonly implemented approach in the Swift developer Community. What are your thoughts about adopting this widely-used operator into the standard library?
> 
> guard !lastItem.isEmpty else { return }
> let lastItem = array.last !! "Array must be non-empty"
> 
> Details here:  https://gist.github.com/erica/423e4b1c63b95c4c90338cdff4939a9b <https://gist.github.com/erica/423e4b1c63b95c4c90338cdff4939a9b>
> 
> Thank you for your thoughtful feedback, -- E
> 
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