<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 5 May 2017, at 09:24, Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" class="">xiaodi.wu@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">On Fri, May 5, 2017 at 2:22 AM, David Hart <span dir="ltr" class=""><<a href="mailto:david@hartbit.com" target="_blank" class="">david@hartbit.com</a>></span> wrote:<br class=""><div class="gmail_extra"><div class="gmail_quote"><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=""><br class=""><div class=""><span class=""><blockquote type="cite" class=""><div class="">On 5 May 2017, at 07:56, Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" target="_blank" class="">xiaodi.wu@gmail.com</a>> wrote:</div><br class="m_2990998714880040230Apple-interchange-newline"><div class=""><div dir="ltr" class="">On Fri, May 5, 2017 at 12:54 AM, David Hart <span dir="ltr" class=""><<a href="mailto:david@hartbit.com" target="_blank" class="">david@hartbit.com</a>></span> wrote:<br class=""><div class="gmail_extra"><div class="gmail_quote"><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 dir="auto" class=""><span class="m_2990998714880040230gmail-"><div class=""><br class=""></div><div class="">On 5 May 2017, at 07:17, Robert Widmann via swift-evolution <<a href="mailto:swift-evolution@swift.org" target="_blank" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""></div><blockquote type="cite" class=""><div class=""><div class="">On the contrary, this is precisely what it means to deprecate tuple shuffles. You can’t map common parlance onto this term; the proposal and the Twitter thread weren’t merely about reordering arguments.</div><div class=""><br class=""></div><div class=""><blockquote type="cite" class=""><div class="">but it is entirely another ballgame to remove labels from tuple patterns altogether.</div></blockquote><br class=""></div><div class="">It’s really not. Let me demonstrate:</div><div class=""><br class=""></div><div class=""><blockquote type="cite" class=""><div class=""><div class="gmail_quote"><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">To be clear, are you proposing the prohibition of *adding or removing* labels as well? A previous discussion on tuple shuffling on this list saw consensus that assigning a value of type (label1: T, label2: U) to a variable of type (T, U) and vice versa should absolutely be supported, whether or not reordering is permitted.</blockquote></div></div></blockquote><br class=""></div><div class="">I am not proposing any changes to switching parameter labels through well-typed re-assignments. This is absolutely still going to be allowed:</div><div class=""><br class=""></div><div class=""><div style="margin:0px;font-size:11px;line-height:normal;font-family:menlo" class=""><div style="margin:0px;line-height:normal" class=""><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)" class="">var</span><span style="font-variant-ligatures:no-common-ligatures" class=""> z : (</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)" class="">Int</span><span style="font-variant-ligatures:no-common-ligatures" class="">, </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)" class="">Int</span><span style="font-variant-ligatures:no-common-ligatures" class="">) = (</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)" class="">0</span><span style="font-variant-ligatures:no-common-ligatures" class="">, </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)" class="">0</span><span style="font-variant-ligatures:no-common-ligatures" class="">)</span></div><div style="margin:0px;line-height:normal" class=""><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)" class="">var</span><span style="font-variant-ligatures:no-common-ligatures" class=""> w : (x : </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)" class="">Int</span><span style="font-variant-ligatures:no-common-ligatures" class="">, y : </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)" class="">Int</span><span style="font-variant-ligatures:no-common-ligatures" class="">) = (</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)" class="">5</span><span style="font-variant-ligatures:no-common-ligatures" class="">, </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)" class="">10</span><span style="font-variant-ligatures:no-common-ligatures" class="">)</span></div><div style="margin:0px;line-height:normal" class=""><span style="font-variant-ligatures:no-common-ligatures" class="">z = w</span></div><div style="margin:0px;line-height:normal" class=""><span style="font-variant-ligatures:no-common-ligatures" class="">w = z</span></div></div></div><div style="margin:0px;font-size:11px;line-height:normal;font-family:menlo" class=""><span style="font-variant-ligatures:no-common-ligatures" class=""><br class=""></span></div><div style="margin:0px;font-size:11px;line-height:normal;font-family:menlo" class=""><div style="font-family:helvetica;font-size:12px" class="">This is modeled internally with a tuple shuffle, but not the kind of shuffle I’m interested in banning. It’s a far simpler kind of </div><div style="font-family:helvetica;font-size:12px" class=""><br class=""></div><div style="font-family:helvetica;font-size:12px" class=""><blockquote type="cite" class=""><div class=""><div class="gmail_quote"><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">And how about *restating* existing labels without any adding or removing? To be clear:<br class=""><br class="">```<br class="">let (partialValue: v, overflow: o) = 42.addingReportingOverflow(42)<br class="">```<br class=""><br class="">...involves absolutely no changes in labels whatsoever. The return type is (partialValue: Int, overflow: ArithmeticOverflow).<br class=""></blockquote></div></div></blockquote><div style="font-family:helvetica;font-size:12px" class=""><br class=""></div><div style="font-family:helvetica;font-size:12px" class="">That, however, is a kind of shuffle I intend to deprecate here. This kind of pattern is subject to the “arcane syntax” part of the proposal.</div><br class=""><blockquote type="cite" class=""><div class=""><div class="gmail_quote"><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"><br class="">Either one of these scenarios is commonly used, and it is astonishing to me that they would be eliminated.</blockquote></div></div></blockquote><br class=""></div><div style="font-family:helvetica;font-size:12px" class="">Do you have proof of that claim? I have never seen the relevant kinds of tuple shuffle used before, and I doubt you have either before today.</div></div></div></blockquote><div class=""><br class=""></div></span><div class="">For what it's worth, I thought I knew Swift inside out and I had never seen or used the syntax your are proposing to ban, so I'm all for it.</div></div></blockquote><div class=""><br class=""></div><div class="">If you google "Swift tuple destructuring," it's demonstrated in the third link you can click on. The article is even titled "best practices":</div><div class=""><br class=""></div><div class=""><a href="https://github.com/terhechte/appventure-blog/blob/master/resources/posts/2015-07-19-tuples-swift-advanced-usage-best-practices.org" target="_blank" class="">https://github.com/terhechte/<wbr class="">appventure-blog/blob/master/<wbr class="">resources/posts/2015-07-19-<wbr class="">tuples-swift-advanced-usage-<wbr class="">best-practices.org</a><br class=""></div></div></div></div></div></blockquote><div class=""><br class=""></div></span><span class=""><div class="">I do know and use tuple destructuring. But AFAIK, that’s not the syntax Robert wants to ban: its the labels in that syntax. As he says:</div><div class=""><br class=""></div><div class=""><i class="">Note that a tuple shuffle is distinct from a re-assignment through a tuple pattern. For example, this series of statements will continue to function as before:</i></div></span><div class=""><div class="h5"><div class=""><i class="">(z, y, x) = (x, z, y)</i></div></div></div></div></div></blockquote><div class=""><br class=""></div><div class="">I'n not saying that you don't know about tuple destructuring. I'm saying that the particular feature Robert wants to ban is covered in the article I linked to, which at least Google thinks is one of the most relevant articles on tuple destructuring in Swift. So, it's not as rare as Robert makes it out to be; plenty of people have talked about it.</div></div></div></div></div></blockquote><div><br class=""></div><div>The article is still called "Advanced Usage”. Its difficult to state how rarely or common a feature is used but my intuition tells me this is a very rare feature. If we’ve discussed it on this list, it has escaped me. And I’ve never seen it in the wild.</div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><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=""><div class=""><div class="h5"><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><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 dir="auto" class=""><div class=""><div class="m_2990998714880040230gmail-h5"><blockquote type="cite" class=""><div class=""><div style="margin:0px;font-size:11px;line-height:normal;font-family:menlo" class=""><div style="font-family:helvetica;font-size:12px" class="">~Robert Widmann</div></div><br class=""><div class=""><blockquote type="cite" class=""><div class="">On May 5, 2017, at 12:53 AM, Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" target="_blank" class="">xiaodi.wu@gmail.com</a>> wrote:</div><br class="m_2990998714880040230gmail-m_1742082391064118614Apple-interchange-newline"><div class=""><div class="">Ah, I see from your proposed grammar update: you're proposing to prohibit the use of labels entirely in a tuple pattern.</div><div class=""><br class=""></div><div class="">This is much more than just prohibiting tuple shuffling, and I'm rather disappointed that you described such a dramatic change using a corner case. There are very good reasons why someone finds 'let (y: x, x: y) = (x: 1, y: 2)' confusing and would support its removal, but it is entirely another ballgame to remove labels from tuple patterns altogether.</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div class="gmail_quote"><div class="">On Thu, May 4, 2017 at 23:47 Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" target="_blank" class="">xiaodi.wu@gmail.com</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">Now I'm confused. The ordinary meaning of the word "shuffle" is not changing but rather reordering, and all of your examples are of reordering.<br class=""><br class="">To be clear, are you proposing the prohibition of *adding or removing* labels as well? A previous discussion on tuple shuffling on this list saw consensus that assigning a value of type (label1: T, label2: U) to a variable of type (T, U) and vice versa should absolutely be supported, whether or not reordering is permitted.<br class=""><br class="">And how about *restating* existing labels without any adding or removing? To be clear:<br class=""><br class="">```<br class="">let (partialValue: v, overflow: o) = 42.addingReportingOverflow(42)<br class="">```<br class=""><br class="">...involves absolutely no changes in labels whatsoever. The return type is (partialValue: Int, overflow: ArithmeticOverflow).<br class=""><br class="">Either one of these scenarios is commonly used, and it is astonishing to me that they would be eliminated.<br class=""><br class=""><div class="gmail_quote"><div class="">On Thu, May 4, 2017 at 23:28 Robert Widmann <<a href="mailto:devteam.codafi@gmail.com" target="_blank" class="">devteam.codafi@gmail.com</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=""><div class=""><div id="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128AppleMailSignature" class="">That doesn't involve a parameter <i class="">reordering</i>, but because it changes argument labels it's a shuffle.</div><div id="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128AppleMailSignature" class=""><br class=""></div>~Robert Widmann</div><div class=""><br class="">2017/05/05 0:16、Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" target="_blank" class="">xiaodi.wu@gmail.com</a>> のメッセージ:<br class=""><br class=""></div></div><div class=""><blockquote type="cite" class=""><div class=""><div class="">Robert,</div><div class=""><br class=""></div><div class="">As I mentioned on Twitter, getting rid of tuple shuffles would not cure your example, which does not involve a shuffle. Unless you're proposing to disallow the use of labels during destructuring entirely, which I would think to be very much unacceptable. Example:</div><div class=""><br class=""></div><div class="">```</div><div class="">let (partialValue: v, overflow: o) = 42.addingReportingOverflow(42)</div><div class="">```</div><div class=""><br class=""></div><div class="">This involves no shuffling and should absolutely remain allowed.</div><div class=""><br class=""></div><div class=""><br class=""><div class="gmail_quote"><div class="">On Thu, May 4, 2017 at 21:15 Robert Widmann via swift-evolution <<a href="mailto:swift-evolution@swift.org" 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="word-wrap:break-word" class="">Hi all,<div class=""><br class=""></div><div class="">So sorry that this proposal comes so late in the game, but I feel it’s too important not to bring it to the attention of the community now. Attached is a proposal to deprecate a language feature many of you will probably have never had the chance to use: Tuple Shuffles. I’ve attached a copy of the first draft of the proposal below, but the latest copy can be read on <a href="https://github.com/apple/swift-evolution/pull/705/files" target="_blank" class="">Github</a>.</div><div class=""><br class=""></div><div class="">Thanks!</div><div class=""><br class=""></div><div class="">~Robert Widmann</div><div class=""><br class=""></div><div class=""><h1 style="box-sizing:border-box;margin:0px 0px 16px;line-height:1.25;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';background-color:rgb(255,255,255)" class="">Deprecate Tuple Shuffles</h1><ul style="box-sizing:border-box;padding-left:2em;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class=""><li style="box-sizing:border-box" class="">Proposal: <a href="https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-filename.md" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none" target="_blank" class="">SE-NNNN</a></li><li style="box-sizing:border-box;margin-top:0.25em" class="">Authors: <a href="https://github.com/codafi" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none" target="_blank" class="">Robert Widmann</a></li><li style="box-sizing:border-box;margin-top:0.25em" class="">Review Manager: TBD</li><li style="box-sizing:border-box;margin-top:0.25em" class="">Status: <span style="box-sizing:border-box;font-weight:600" class="">Awaiting review</span></li></ul><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';background-color:rgb(255,255,255)" class=""><a id="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920user-content-introduction" class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920anchor" href="https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#introduction" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none;float:left;padding-right:4px;line-height:1" target="_blank"><u class=""></u><u class=""></u><u class=""></u><u class=""></u></a>Introduction</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">This proposal seeks the deprecation of a little-known feature of Swift called a "Tuple Shuffle".</p><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';background-color:rgb(255,255,255)" class=""><a id="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920user-content-motivation" class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920anchor" href="https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#motivation" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none;float:left;padding-right:4px;line-height:1" target="_blank"><u class=""></u><u class=""></u><u class=""></u><u class=""></u></a>Motivation</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">A tuple-shuffle is an undocumented feature of Swift in which one can re-order the indices of a tuple by writing a pattern that describes a permutation in a syntax reminiscent of adding type-annotations to a parameter list:</p><div class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight-source-swift" style="box-sizing:border-box;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)"><pre style="box-sizing:border-box;font-family:sfmono-regular,consolas,'liberation mono',menlo,courier,monospace;font-size:13.600000381469727px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(246,248,250);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;word-break:normal" class=""><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">let</span> a <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">=</span> (<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">x</span>: <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">1</span>, <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">y</span>: <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">2</span>)
<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">var</span> b<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">:</span> (<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">y</span>: <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Int</span>, <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">x</span>: <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Int</span>)
b <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">=</span> a</pre></div><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">It can be used to simultaneously destructure and reorder a tuple:</p><div class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight-source-swift" style="box-sizing:border-box;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)"><pre style="box-sizing:border-box;font-family:sfmono-regular,consolas,'liberation mono',menlo,courier,monospace;font-size:13.600000381469727px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(246,248,250);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;word-break:normal" class=""><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">let</span> tuple <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">=</span> (<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">first</span>: <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">0</span>, <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">second</span>: (<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">x</span>: <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">1</span>, <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">y</span>: <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">2</span>))
<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">let</span> (<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">second</span>: (<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">x</span>: b, <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">y</span>: c), <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">first</span>: a) <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">=</span> tuple</pre></div><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">It can also be used to map parameter labels out of order in a call expression:</p><div class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight-source-swift" style="box-sizing:border-box;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)"><pre style="box-sizing:border-box;font-family:sfmono-regular,consolas,'liberation mono',menlo,courier,monospace;font-size:13.600000381469727px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(246,248,250);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;word-break:normal" class=""><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">func</span> <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-en" style="box-sizing:border-box;color:rgb(121,93,163)">foo</span>(<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-smi" style="box-sizing:border-box;color:rgb(51,51,51)"><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-en" style="box-sizing:border-box;color:rgb(121,93,163)">_</span></span> : (x : <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Int</span>, y : <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Int</span>)) {}
<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">foo</span>((<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">y</span>: <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">5</span>, <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">x</span>: <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">10</span>)) <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c" style="box-sizing:border-box">//</span> Valid</span></pre></div><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">Note that a tuple shuffle is distinct from a re-assignment through a tuple pattern. For example, this series of statements will continue to function as before:</p><div class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight-source-swift" style="box-sizing:border-box;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)"><pre style="box-sizing:border-box;font-family:sfmono-regular,consolas,'liberation mono',menlo,courier,monospace;font-size:13.600000381469727px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(246,248,250);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;word-break:normal" class=""><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">var</span> x <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">=</span> <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">5</span>
<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">var</span> y <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">=</span> <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">10</span>
<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">var</span> z <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">=</span> <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">15</span>
(z, y, x) <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">=</span> (x, z, y)</pre></div><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">Their inclusion in the language complicates every part of the compiler stack, uses a <a href="https://twitter.com/CodaFi_/status/860246169854894081" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none" target="_blank" class="">syntax that can be confused for type annotations</a>, contradicts the goals of earlier SE's (see <a href="https://github.com/apple/swift-evolution/blob/9cf2685293108ea3efcbebb7ee6a8618b83d4a90/proposals/0060-defaulted-parameter-order.md" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none" target="_blank" class="">SE-0060</a>), and makes non-sensical patterns possible in surprising places.</p><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">Take switch-statements, for example:</p><div class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight-source-swift" style="box-sizing:border-box;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)"><pre style="box-sizing:border-box;font-family:sfmono-regular,consolas,'liberation mono',menlo,courier,monospace;font-size:13.600000381469727px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(246,248,250);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;word-break:normal" class=""><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">switch</span> ((<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">0</span>, <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">0</span>), <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">0</span>){
<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">case</span> (<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">_</span> : <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">let</span> (y, z), <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">_</span> : <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">let</span> s)<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">:</span> () <span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c" style="box-sizing:border-box">//</span> We are forbidden from giving these patterns names other than "_" </span>
<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"></span><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">default</span><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">:</span> ()
}</pre></div><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">This proposal seeks to deprecate them in Swift 3 compatibility mode and enforce that deprecation as a hard error in Swift 4 to facilitate their eventual removal from the language.</p><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';background-color:rgb(255,255,255)" class=""><a id="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920user-content-proposed-solution" class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920anchor" href="https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#proposed-solution" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none;float:left;padding-right:4px;line-height:1" target="_blank"><u class=""></u><u class=""></u><u class=""></u><u class=""></u></a>Proposed solution</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">Construction of Tuple Shuffle Expressions will become a warning in Swift 3 compatibility mode and will be a hard-error in Swift 4.</p><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';background-color:rgb(255,255,255)" class=""><a id="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920user-content-detailed-design" class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920anchor" href="https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#detailed-design" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none;float:left;padding-right:4px;line-height:1" target="_blank"><u class=""></u><u class=""></u><u class=""></u><u class=""></u></a>Detailed design</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">In addition to the necessary diagnostics, the grammar will be ammended to simplify the following productions:</p><div class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920highlight-source-diff" style="box-sizing:border-box;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)"><pre style="box-sizing:border-box;font-family:sfmono-regular,consolas,'liberation mono',menlo,courier,monospace;font-size:13.600000381469727px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(246,248,250);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;word-break:normal" class="">tuple-pattern → (tuple-pattern-element-list <opt>)
tuple-pattern-element-list → tuple-pattern-element | tuple-pattern-element , tuple-pattern-element-list
<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-md" style="box-sizing:border-box;color:rgb(189,44,0);background-color:rgb(255,236,236)"><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-md" style="box-sizing:border-box">-</span> tuple-pattern-element → pattern | identifier:pattern</span>
<span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-mi1" style="box-sizing:border-box;color:rgb(85,165,50);background-color:rgb(234,255,234)"><span class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920pl-mi1" style="box-sizing:border-box">+</span> tuple-pattern-element → pattern</span></pre></div><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';background-color:rgb(255,255,255)" class=""><a id="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920user-content-impact-on-existing-code" class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920anchor" href="https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#impact-on-existing-code" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none;float:left;padding-right:4px;line-height:1" target="_blank"><u class=""></u><u class=""></u><u class=""></u><u class=""></u></a>Impact on Existing Code</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255)" class="">Because very little code is intentionally using Tuple Shuffles, impact on existing code will be negligible but not non-zero.</p><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';background-color:rgb(255,255,255)" class=""><a id="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920user-content-alternatives-considered" class="m_2990998714880040230gmail-m_1742082391064118614m_-2923833813410546814m_-383149691311174760m_1919140766618257128m_5304457839982547920anchor" href="https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#alternatives-considered" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none;float:left;padding-right:4px;line-height:1" target="_blank"><u class=""></u><u class=""></u><u class=""></u><u class=""></u></a>Alternatives considered</h2><div style="box-sizing:border-box;margin-top:0px;color:rgb(36,41,46);font-family:-apple-system,blinkmacsystemfont,'segoe ui',helvetica,arial,sans-serif,'apple color emoji','segoe ui emoji','segoe ui symbol';font-size:16px;background-color:rgb(255,255,255);margin-bottom:0px" class="">Continue to keep the architecture in place to facilitate this feature.</div></div></div>______________________________<wbr class="">_________________<br class="">
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