<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="">Hi Mark,<div class=""><br class=""></div><div class="">one example of what was possible in Swift 3 but not convenient in Swift4 as it stands is the following:</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""> <span style="color: #ba2da2" class="">let</span> bookTuples = [(<span style="color: #272ad8" class="">1</span>, <span style="color: #d12f1b" class="">"john"</span>, <span style="color: #d12f1b" class="">"book"</span>, <span style="color: #d12f1b" class="">"novel"</span>, <span style="color: #272ad8" class="">9.99</span>, []),</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""> (<span style="color: #272ad8" class="">2</span>, <span style="color: #d12f1b" class="">"john"</span>, <span style="color: #d12f1b" class="">"book"</span>, <span style="color: #d12f1b" class="">"novel"</span>, <span style="color: #272ad8" class="">9.99</span>, [<span style="color: #d12f1b" class="">"chapt1"</span>, <span style="color: #d12f1b" class="">"chapt2"</span>])]</div><div style="margin: 0px; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""> <span style="color: #3e1e81" class="">print</span>(<span style="color: #d12f1b" class="">"""</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <?xml version="1.0"?></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <catalog></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #d12f1b" class=""> </span>\<span style="color: #d12f1b" class="">(</span>bookTuples.<span style="color: #3e1e81" class="">map</span> {</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><b class=""> (id, author, title, genre, price, chapters) <span style="color: #ba2da2" class="">in</span> <span style="color: #d12f1b" class="">"""</span></b></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <book id="bk<span style="color: #000000" class="">\</span>(<span style="color: #000000" class="">id)</span>" empty=""></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <author><span style="color: #000000" class="">\</span>(<span style="color: #000000" class="">author</span>)</author></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <title><span style="color: #000000" class="">\</span>(<span style="color: #000000" class="">title</span>)</title></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <genre><span style="color: #000000" class="">\</span>(<span style="color: #000000" class="">genre</span>)</genre></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <price><span style="color: #000000" class="">\</span>(<span style="color: #000000" class="">price</span>)</price></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <chapters></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <span style="color: #000000" class="">\</span>(<span style="color: #000000" class="">chapters.</span><span style="color: #3e1e81" class="">map</span><span style="color: #000000" class=""> {</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""> (heading) <span style="color: #ba2da2" class="">in</span> <span style="color: #d12f1b" class="">"""</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> <heading><span style="color: #000000" class="">\</span>(<span style="color: #000000" class="">heading</span>)</heading></div><div style="margin: 0px; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> """<span style="color: #000000" class="">}.</span><span style="color: #3e1e81" class="">joined</span><span style="color: #000000" class="">(separator:</span>""<span style="color: #000000" class="">)</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""><span style="color: #000000" class=""> </span>) </chapters></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> </book></div><div style="margin: 0px; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> """<span style="color: #000000" class="">}.</span><span style="color: #3e1e81" class="">joined</span><span style="color: #000000" class="">(separator:</span>""<span style="color: #000000" class="">)</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""> <span style="color: #d12f1b" class="">)</catalog></span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(209, 47, 27); background-color: rgb(255, 255, 255);" class=""> """<span style="color: #000000" class="">)</span></div><div class=""><span style="color: #000000" class=""><br class=""></span></div><div class=""><span style="color: #000000" class="">It would be great if this functionality could be preserved somehow. ((double brackets)) </span>perhaps</div><div class="">but it would help library maintainers if this could also be back ported into Swift 3.2.</div><div class=""><br class=""></div><div class=""><span style="color: #000000" class="">-John</span></div><div class=""><span style="color: #000000" class=""><br class=""></span></div><div><blockquote type="cite" class=""><div class="">On 6 Jun 2017, at 18:10, Mark Lacey 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=""><div 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;" class=""><blockquote type="cite" class=""><div class=""><br class="Apple-interchange-newline">On Jun 6, 2017, at 8:42 AM, Ray Fix 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=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""><br class=""></div><div class="">FWIW, after doing a project migration last night and this morning, I am reluctantly +1 for reverting SE-0110 and seeing a new proposal that can be properly evaluated. The split-the-difference compromise mentioned seems like just that, a compromise that will need to be revisited anyway.</div><div class=""><br class=""></div><div class="">While I agreed with the spirit of the original proposal, the assertion that "Minor changes to user code may be required if this proposal is accepted.” seems like it underestimated the magnitude of the impact. In almost every case, my code lost clarity.</div></div></div></blockquote><div class=""><br class=""></div><div class="">Did you run into issues other than the “tuple destructuring” issue that began this thread?</div><div class=""><br class=""></div><div class="">If so, can you provide some examples to illustrate what other issues people are hitting in practice?</div><div class=""><br class=""></div><div class="">I put “tuple destructuring” in quotes here because although it looks very much like what is happening in Swift 3 and earlier, there was no real tuple destructuring support in parameters (as evidenced by the fact that things like (x, (y, z)) never worked).</div></div><div 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;" class=""><br class=""></div><div 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;" class="">The behavior of allowing:</div><div 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;" class=""> [“key” : 1].map { key, value in … }</div><div 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;" class="">is the result of allowing the two-argument closure to be passed to a function (map) that expects a one-argument function parameter where the argument is a two element tuple.</div><div 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;" class=""><br class=""></div><div 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;" class="">I don’t think anyone disagrees that removing this functionality without simultaneously providing a real destructuring feature regresses the usability of the language where closures are concerned.</div><div 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;" class=""><br class=""></div><div 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;" class="">Understanding other fallout from SE-0110 will be helpful in guiding the decision of how to move forward from here.</div><div 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;" class=""><br class=""></div><div 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;" class="">Mark</div><div 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;" class=""><br class=""><blockquote type="cite" class=""><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""><br class=""></div><div class="">Other aspects of the migration went quite smoothly.</div><div class=""><br class=""></div><div class="">BTW, if I were at WWDC this year I would be in the Swift lab pestering them about this. Hopefully that feedback is happening. :)</div><div class=""><br class=""></div><div class="">Ray</div><div class=""><br class=""></div><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Jun 6, 2017, at 8:22 AM, Shawn Erickson 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=""><div 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;"><div class="gmail_quote"><div class=""><br class="Apple-interchange-newline">On Tue, Jun 6, 2017 at 7:18 AM Gwendal Roué 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: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-style: solid; border-left-color: rgb(204, 204, 204); padding-left: 1ex;"><div class="" style="word-wrap: break-word;"><br class=""><div class=""><blockquote type="cite" class=""><div class="">Le 6 juin 2017 à 15:30, Vladimir.S <<a href="mailto:svabox@gmail.com" target="_blank" class="">svabox@gmail.com</a>> a écrit :</div><br class="m_-6400720107763134181Apple-interchange-newline"><div class=""><span class="" style="font-family: Helvetica; font-size: 14px; 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; float: none; display: inline !important;">I'm just trying to understand your opinion.</span><br class="" style="font-family: Helvetica; font-size: 14px; 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;"><span class="" style="font-family: Helvetica; font-size: 14px; 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; float: none; display: inline !important;">Let me know, what result do you *expect* for this Swift4 code given what SE-0066 requires for function types:</span><br class="" style="font-family: Helvetica; font-size: 14px; 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;"><br class="" style="font-family: Helvetica; font-size: 14px; 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;"><span class="" style="font-family: Helvetica; font-size: 14px; 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; float: none; display: inline !important;">func foo(x : (Int, Int))->() {}</span><br class="" style="font-family: Helvetica; font-size: 14px; 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;"><br class="" style="font-family: Helvetica; font-size: 14px; 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;"><span class="" style="font-family: Helvetica; font-size: 14px; 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; float: none; display: inline !important;">print(type(of: foo)) // ??</span><br class="" style="font-family: Helvetica; font-size: 14px; 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;"><span class="" style="font-family: Helvetica; font-size: 14px; 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; float: none; display: inline !important;">print(foo is (_: Int, _: Int)->()) // ??</span></div></blockquote><br class=""></div></div><div class="" style="word-wrap: break-word;"><div class="">I couldn't care less.</div><div class=""><br class=""></div><div class="">What I care about: the code regressions introduced by SE-0110 (look at previous messages in this long thread, and the ridiculous state of closures that eat tuples), and the migration bugs (look at Xcode 9 release notes).</div></div></blockquote><div class=""><br class=""></div><div class="">Note that many of Apple's swift team are likely swamped with WWDC at the moment. They are also dealing with merging out their private changes announced so far at WWDC. Xcode 9 is prerelease still so expect things to get revised to some degree before the final release.</div><div class=""><br class=""></div><div class="">Not say to not voice concerns but at this time some patience will be needed.</div><div class=""><br class=""></div><div class="">-Shawn</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 class="" style="word-wrap: break-word;"><div class=""></div></div></blockquote></div></div><span 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; float: none; display: inline !important;">_______________________________________________</span><br class="" style="font-family: Helvetica; font-size: 12px; 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