> On 28 Jun 2017, at 17:35, Ben Cohen via swift-evolution > <swift-evolution@swift.org> wrote: > > >> On Jun 28, 2017, at 6:03 AM, Erica Sadun via swift-evolution >> <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote: >> >> In general, does everyone prefer `?? () -> Never` or `!! () -> Never`? I can >> argue both ways, with the goal in reading code as "unwrap or die". >> > > > Personally, I strongly prefer `foo !! "explanation"` over `foo ?? > fatalError()`. I don’t think adding another operator for what is a very > common need is a concern, and is easier to read at a glance than the > ??/fatalError combo. There is a bit of cognitive dissonance
Actually, the cognitive dissonance argument is a strong one. Its true that ?? doesn’t evoke trapping. > between ??, a normally-fluffy nonthreatening defaulting operator, and > fatalError, a scary beware operator. `!!` OTOH matches `!` in clearly > flagging the unwrap as unsafe and that your program will exit. I also think > it would be easier to explain `!!` to beginners as part of a wider story > explaining optionals in general, unwraps, what `nil` means and what `!` means > etc. Whereas `foo ?? Never` requires a lot of heavy lifting to understand > how/why it works – we might all understand it, but that understanding is > built on a lot of foundational understanding. > > I also think a `Never` type would be very useful. Just that for this > particular case, `!!` is still worth adding too. > > > _______________________________________________ > swift-evolution mailing list > swift-evolution@swift.org > https://lists.swift.org/mailman/listinfo/swift-evolution
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