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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>I think I revise what I said about value semantics in my last post.</p>
<pre><code class="swift">let chain: T = foo.a()
let new = chain
new. // should not see `a` here
</code></pre>
<p>It’s more something like a local scoped chain. I’m not sure how to call it correctly here. I’m not a native English speaker. =)</p>
<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_1482751593527631872" 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 26. Dezember 2016 um 12:11:23, 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>By ‘calling once’ I meant, calling once at a single permutation
chain. If the chain is escaped or followed by a non-permuting
member that returns the same protocol, you’d have the ability to
use all members at the starting point of the new chain.</p>
<pre><code class="swift">permuting protocol T {
func a()
func b()
func c()
func d()
}
var foo: T = …
func boo(_ val: T) -> U {
// Here val escapes the chain and creates a new one
// That means that you can create a local permutation chain here again
val.a() // we can use `a` here
return …
}
boo(foo.a()) // a is immediately invoked here
</code></pre>
<p>I imagine this keyword to follow value semantics, so that any
possible mutation is handled locally with a nice extra ability of
permutation member chaining.</p>
<p>Did I understood your point correctly here?</p>
<hr>
<p>Sure the idea needs to be more fleshed out, but I’m curious if
that’s something that we might see in Swift one day. :)</p>
</div>
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<br></div>
<br>
<div id="bloop_sign_1482749838336907008" 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 26. Dezember 2016 um 11:50:50, Xiaodi Wu
(<a href="mailto:xiaodi.wu@gmail.com">xiaodi.wu@gmail.com</a>)
schrieb:</p>
<blockquote type="cite" class="clean_bq">
<div><span><span style="color: rgb(0, 0, 0); font-family: 'helvetica Neue', helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); display: inline !important; float: none;">
Given `foo: T` and methods a(), b(), c(), d(), each of which can
only be called once, how can the return value of these methods be
represented in the type system?</span><br style="color: rgb(0, 0, 0); font-family: 'helvetica Neue', helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">
<br style="color: rgb(0, 0, 0); font-family: 'helvetica Neue', helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">
<span style="color: rgb(0, 0, 0); font-family: 'helvetica Neue', helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); display: inline !important; float: none;">
That is, if `foo.a()` can be passed as an argument to an arbitrary
function of type `(T) -> U`, either the function cannot
immediately invoke a(), in which case foo is not of type T, or it
can immediately invoke a(), in which case your keyword does not
work.</span></span></div>
</blockquote>
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<div class="bloop_markdown"></div>
</div></div></span></blockquote></div><div class="bloop_markdown"><p></p></div></body></html>