<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=""><br class=""><div><blockquote type="cite" class=""><div class="">On 4 Oct 2016, at 16:30, Tim Vermeulen 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=""><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="">I think I agree with you. The postfix `!` operator is always shorthand for `fatalError()` (and some more syntax), and it would fit nicely with `default: fatalError()`.<div class=""><br class=""></div><div class="">The Swift usage of `?` is indeed different than `default: break` would do, so `switch?` wouldn’t convey the right message. I hadn’t given it enough thought. I still think a shorthand for `default: break` would be _nice_, but it surely shouldn’t change the `?` consistency, it also shouldn’t replace the current `switch` (as exhaustiveness is very useful) and it’s probably not worth introducing new syntax for.</div><div class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On 4 Oct 2016, at 16:36, Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" class="">xiaodi.wu@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">There is a plausible argument for `switch!`, because it is not possible for the compiler to prove exhaustiveness in all circumstances where you might know it to be the case.<br class=""><br class="">However, I'd be very against `switch?`: it undermines the exhaustiveness guarantee of the switch statement and is wholly inconsistent with Swift usage of `?`, which indicates the possibility of an Optional. We simply don't need a new spelling for `default: break`.</div></blockquote></div></div></div></div></blockquote><br class=""></div><div>I agree with Tim; I'm a +1 for switch! for a convenient means of erroring out, but I think switch? is a bit too different from normal usage of the question-mark.</div><div><br class=""></div><div>One other alternative might be if there could be some kind of switch else syntax, kind of like a guard statement, allowing options on what to do? Only problem is how best to structure it, as the use of break might confusing as to its scope, like so:</div><div><br class=""></div><div><font face="Monaco" class=""><span class="Apple-tab-span" style="white-space:pre"> </span>switch(foo) else break { // Break from the switch, or the enclosing block?</font></div><div><br class=""></div><div>So I'm not 100% on that. But it would mean that switch! would be a shorthand for switch else fatalError().</div></body></html>