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

[Jacob Bandes-Storch]

I've found a similar thing useful, but with Errors instead of fatalErroring:

infix operator ?! : NilCoalescingPrecedence

func ?!<T>(lhs: T?, rhs: @autoclosure () -> Error) throws -> T {
    if let lhs = lhs { return lhs }
    throw rhs()
}

let x = try failableFunc() ?! MyError.somethingFailed


On Tue, Jun 27, 2017 at 10:29 AM, Adrian Zubarev via swift-evolution <
swift-evolution at swift.org> wrote:

> +1 I had a slightly different implementation.
>
> https://gist.github.com/DevAndArtist/dad641ee833e60b02fd1db2dbb488c6a
>
> //
> // UnwrapOrTrap.swift
> //
> infix operator ?! : NilCoalescingPrecedence
>
> /// Performs a nil-coalescing operation, returning the wrapped value of an
> /// `Optional` instance or uses the rhs function to stop the program.
> ///
> /// - Parameters:
> ///   - optional: An optional value.
> ///   - noreturn: A function to stop the programm.
> func ?!<T>(optional: T?, noreturn: @autoclosure () -> Never) -> T {
>    switch optional {
>    case .some(let value):
>       return value
>    case .none:
>       noreturn()
>    }
> }
>
>
>
> --
> Adrian Zubarev
> Sent with Airmail
>
> Am 27. Juni 2017 um 19:25:15, Erica Sadun via swift-evolution (
> swift-evolution at swift.org) schrieb:
>
> 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
>
> Thank you for your thoughtful feedback, -- E
>
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