<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">One argument against `?? () -> Never` is that `func f() -> Never { while true {} }` will also work.<div class=""><br class=""></div><div class="">Max</div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Jun 28, 2017, at 8:35 AM, Ben Cohen <<a href="mailto:ben_cohen@apple.com" class="">ben_cohen@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Jun 28, 2017, at 6:03 AM, Erica Sadun via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">In general, does everyone prefer `?? () -> Never` or `!! () -> Never`? I can argue both ways, with the goal in reading code as "unwrap or die".</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class="Apple-interchange-newline"></div></blockquote></div><div class=""><br class=""></div>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 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.<div class=""><div class=""><br class=""></div><div class="">I also think a `Never` type would be very useful. Just that for this particular case, `!!` is still worth adding too.</div></div><div class=""><br class=""></div><div class=""><br class=""></div></div></div></blockquote></div><br class=""></div></body></html>