<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="">I'll give this a kick around as soon as I get a moment and revise. I am slightly concerned that we discussed variations of this in the past (throwing if memory serves, with `Error` on the rhs) and that it broke the expectations of nil-coalescing. <div class=""><br class=""></div><div class="">In general, does everyone prefer `?? () -> Never` or `!! () -> Never`? I can argue both ways, with the goal in reading code as "unwrap or die".<br class=""><div class=""><br class=""></div><div class=""><div class="">-- E</div><div class=""><br class=""><div class=""><div><blockquote type="cite" class=""><div class="">On Jun 27, 2017, at 7:16 PM, Max Moiseev 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=""><div class="">The compatibility testing revealed no related errors. And the full test suite only shows one that I listed already.</div><div class=""><br class=""></div><div class="">Max</div><div class=""><br class=""></div><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Jun 27, 2017, at 3:28 PM, Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" class="">xiaodi.wu@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">This solution is nifty indeed, and has the chief advantage of working.<br class=""><div class="gmail_quote"><div dir="ltr" class="">On Tue, Jun 27, 2017 at 16:55 Max Moiseev via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class=""><div class=""><blockquote type="cite" class=""><div class="">On Jun 27, 2017, at 1:03 PM, Adrian Zubarev <<a href="mailto:adrian.zubarev@devandartist.com" target="_blank" class="">adrian.zubarev@devandartist.com</a>> wrote:</div><br class="m_-8152363839179283491Apple-interchange-newline"><div class=""><div class="m_-8152363839179283491bloop_markdown" style="font-family:Helvetica,Arial;font-size:13px;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;background-color:rgb(254,254,254)"><p style="margin:15px 0px" class="">How about?</p><pre style="margin:15px 0px;font-family:Menlo,Consolas,'Liberation Mono',Courier,monospace;font-size:10pt;border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;background-color:rgb(248,248,248);color:inherit;border:1px solid rgb(204,204,204);overflow:auto;padding:4px 8px;word-break:normal;word-wrap:normal" class=""><code style="font-family:Menlo,Consolas,'Liberation Mono',Courier,monospace;font-size:10pt;border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;background-color:rgb(248,248,248);color:inherit;border:0px;margin:0px;padding:0px;word-break:normal;word-wrap:normal" class="">public func ?? <T>(optional: T?, noreturnOrError: @autoclosure () throws -> Never) rethrows -> T {
switch optional {
case .some(let value):
return value
case .none:
try noreturnOrError()
}
}
</code></pre><div style="margin:15px 0px" class=""><br class="m_-8152363839179283491webkit-block-placeholder"></div></div></div></blockquote></div></div><div style="word-wrap:break-word" class=""><div class="">Yeah, I saw your email right after I sent mine =)</div><div class="">This works, I tried it and also ran the test suite. There was only one error.</div><div class=""><br class=""></div><div class=""><font face="SFMono-Regular" class=""><span style="font-size:11px" class=""> var s: String = ns ?? "str" as String as String // expected-error{{cannot convert value of type 'NSString?' to expected argument type 'String?'}}<br class=""> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br class=""> cannot convert value of type 'String' to expected argument type 'NSString'</span></font><br class=""><br class=""><div class=""><br class=""></div><div class="">I now wonder what the effect on the source compatibility suite would be:</div><div class=""><a href="https://github.com/apple/swift/pull/10639" target="_blank" class="">https://github.com/apple/swift/pull/10639</a></div></div></div><div style="word-wrap:break-word" class=""><div class=""><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Max</div></div></div><div style="word-wrap:break-word" class=""><div class=""><br class=""><blockquote type="cite" class=""><div class=""><div class="m_-8152363839179283491bloop_original_html" style="font-family:Helvetica,Arial;font-size:13px;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;background-color:rgb(254,254,254)"><div id="m_-8152363839179283491bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><br class=""></div><br class=""><div id="m_-8152363839179283491bloop_sign_1498593590478208000" class="m_-8152363839179283491bloop_sign"><div style="font-family:helvetica,arial;font-size:13px" class="">-- <br class="">Adrian Zubarev<br class="">Sent with Airmail</div></div><br class=""><p class="m_-8152363839179283491airmail_on" style="margin:15px 0px">Am 27. Juni 2017 um 21:54:57, Max Moiseev via swift-evolution (<a href="mailto:swift-evolution@swift.org" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">swift-evolution@swift.org</a>) schrieb:</p><blockquote type="cite" class="m_-8152363839179283491clean_bq" style="margin:15px 0px"><span style="margin-top:0px;margin-bottom:0px" class=""><div style="word-wrap:break-word" class=""><div class=""></div><div class=""><br class=""><div class=""><blockquote type="cite" style="margin:15px 0px" class=""><div style="margin-top:0px" class="">On Jun 27, 2017, at 10:38 AM, Xiaodi Wu via swift-evolution <<a href="mailto:swift-evolution@swift.org" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">swift-evolution@swift.org</a>> wrote:</div><br class="m_-8152363839179283491Apple-interchange-newline"><div style="margin-bottom:0px" class="">As you write, this operator becomes sugar for “?? fatalError()” once Never becomes a true bottom type.<br class=""><br class="">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?<br class=""></div></blockquote><div class=""><br class=""></div><div class="">I like this idea more than adding an extra operator, but overloading fatalError won’t work now because of <a href="https://github.com/apple/swift/blob/master/stdlib/public/core/Optional.swift#L668" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">https://github.com/apple/swift/blob/master/stdlib/public/core/Optional.swift#L668</a></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><br class=""><blockquote type="cite" style="margin:15px 0px" class=""><div style="margin-top:0px;margin-bottom:0px" class=""><div class="gmail_quote"><div dir="ltr" class="">On Tue, Jun 27, 2017 at 12:25 Erica Sadun via swift-evolution <<a href="mailto:swift-evolution@swift.org" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">swift-evolution@swift.org</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div style="margin-top:0px;word-wrap:break-word" class=""><div class="">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?</div><div class=""><br class=""></div><div class=""><font face="Menlo" class="">guard !lastItem.isEmpty else { return }</font></div><div class=""><font face="Menlo" class="">let lastItem = array.last !! "Array must be non-empty"</font></div><div class=""><br class=""></div><div class="">Details here: <a href="https://gist.github.com/erica/423e4b1c63b95c4c90338cdff4939a9b" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">https://gist.github.com/erica/423e4b1c63b95c4c90338cdff4939a9b</a></div><div class=""><br class=""></div><div class="">Thank you for your thoughtful feedback, -- E</div><div class=""><br class=""></div></div>_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" rel="noreferrer" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br style="margin-bottom:0px" class=""></blockquote></div>_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class=""></div></blockquote></div><br class="">_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" style="color:rgb(65,131,196);background-color:inherit;text-decoration:none" target="_blank" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class=""></div></div></span></blockquote></div><div class="m_-8152363839179283491bloop_markdown" style="font-family:Helvetica,Arial;font-size:13px;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;background-color:rgb(254,254,254)"></div></div></blockquote></div></div>_______________________________________________<br class="">
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