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.error { color:#AA0000; }</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class="bloop_markdown"><p>IMHO the following line of code contains a highly inconsistent syntax, because the rhs uses labels for some sort of assignment, where the lhs just marks a constant/variable after the colon.</p>
<pre><code class="swift">let (x: x, y: y) = (x: 0, y: 0) // valid today
</code></pre>
<p></p></div><div class="bloop_original_html"><style>body{font-family:Helvetica,Arial;font-size:13px}</style><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div> <br> <div id="bloop_sign_1493981025293466112" class="bloop_sign"><div style="font-family:helvetica,arial;font-size:13px">-- <br>Adrian Zubarev<br>Sent with Airmail</div></div> <br><p class="airmail_on">Am 5. Mai 2017 um 12:42:11, Adrian Zubarev (<a href="mailto:adrian.zubarev@devandartist.com">adrian.zubarev@devandartist.com</a>) schrieb:</p> <blockquote type="cite" class="clean_bq"><span><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div></div><div>
<title></title>
<div class="bloop_markdown">
<p>Labels create more harm in tuple destructuring than they
solve.</p>
<pre><code class="swift">let point = (x: 0, y: 0)
let (myX, myY) = point // fine
let (x: my_X, y: my_Y) = point // fine
let tuple = (a: 0, innerTuple: point)
let (myA, myInnerTuple) = tuple
// The following destructuring can extract nested tuples as well
let (a: a, innerTuple: (x: x, y: y)) = tuple // fine
// Let's try the same without labels
let (my_A, (myNewX, myNewY)) = tuple
// error: cannot express tuple conversion '(a: Int, innerTuple: (x: Int, y: Int))' to '(Int, (Int, Int))'
// Wait what? It did worked above with `point`
// Let's try something else
let (a: _, innerTuple: (newX, newY)) = tuple
// '(a: Int, innerTuple: (x: Int, y: Int))' to '(a: Int, innerTuple: (Int, Int))'
// Yet another approach
let (a: _, innerTuple: inner) = tuple // fine
</code></pre>
<p>From this I conclude that tuple destructuring creates a new
tuple, which is not my intention at all, at least not in terms of
extracting data. The types become incompatible with each other if
not labeled properly and that’s why we cannot omit unwanted labels
and are forced to either type them all out to extract nested data
or none of them at all.</p>
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<br></div>
<br>
<div id="bloop_sign_1493980506601995008" class="bloop_sign">
<div style="font-family:helvetica,arial;font-size:13px">
-- <br>
Adrian Zubarev<br>
Sent with Airmail</div>
</div>
<br>
<p class="airmail_on">Am 5. Mai 2017 um 09:32:02, Xiaodi Wu
(<a href="mailto:xiaodi.wu@gmail.com">xiaodi.wu@gmail.com</a>)
schrieb:</p>
<blockquote type="cite" class="clean_bq">
<div>
<div>
<div dir="ltr"><span>On Fri, May 5, 2017 at 2:28 AM, Adrian Zubarev
<span dir="ltr"><<a href="mailto:adrian.zubarev@devandartist.com" target="_blank">adrian.zubarev@devandartist.com</a>></span>
wrote:<br></span>
<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">
<div class="m_-5555134904584300890bloop_markdown">
<p>I’m not arguing to remove all labels in Swift. Labels are great,
this is a fact for sure. The point I was trying to make is that
labels in tuples how either a meaning or not at all.</p>
<pre><code class="m_-5555134904584300890swift">// This is a shortcut for the tuple type `(x: Int, y: Int)`
let foo = (x: 0, y: 0)
// In this case the labels are only used for description,
// they do not server any benefit here are most likely redundant
let (x: x, y: y) = foo
</code></pre>
<p>Labels elsewhere are a different story and I do support the
cosmetic addition Chris Lattner sketched out here: <a href="https://lists.swift.org/pipermail/swift-evolution-announce/2016-July/000233.html" target="_blank">https://lists.swift.org/<wbr>pipermail/swift-evolution-<wbr>announce/2016-July/000233.html</a></p>
<p>However this is about closures and not tuples, I don’t think
this would anyhow affect the removal of labels in tuple
destructuring.</p>
<p>Plus I don’t see this to create an inconsistent in Swift,
because as I already said, labels in tuple destructuring are
useless.</p>
</div>
</div>
</blockquote>
<div>How come? I just illustrated their use. They help humans write
correct code by allowing the compiler to check an assertion that
the human knows which labels go with which positions in the
tuple.</div>
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