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<body><div>Alternatively you can write<br></div>
<div> </div>
<div> subviews.lazy.flatMap({ $0 as? NSButton }).find({ $0.state == NSOnState })<br></div>
<div> </div>
<div>-Kevin Ballard<br></div>
<div> </div>
<div>On Wed, Feb 17, 2016, at 07:12 AM, Maximilian Hünenberger via swift-evolution wrote:<br></div>
<blockquote type="cite"><div> </div>
<div>I think<br></div>
<div> </div>
<div> subviews.find{ ($0 as? NSButton)?.state == NSOnState } as? NSButton<br></div>
<div> </div>
<div>is sufficient and makes it clear that you are searching for a specific type. Even though you have to cast twice I don't think an additional method would be worth its use since it isn't used as often.<br></div>
<div> </div>
<div>- Maximilian<br></div>
<div><div> </div>
<div>Am 17.02.2016 um 10:32 schrieb Marco Masser via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>>:<br></div>
</div>
<blockquote type="cite"><div><div>I just saw this PR and have a quick comment about the implementation: It could be shortened by a few lines using a <span class="colour" style="color:rgb(187, 44, 162)"><span class="font" style="font-family:Menlo"><span class="size" style="font-size:11px">where</span></span></span> clause like this:<br></div>
<div> </div>
<div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span class="colour" style="color:rgb(187, 44, 162)">func</span><span style=""> find(</span><span class="colour" style="color:rgb(187, 44, 162)">@noescape</span><span style=""> predicate: </span><span class="colour" style="color:rgb(79, 129, 135)">Self</span><span style="">.</span><span class="colour" style="color:rgb(112, 61, 170)">Generator</span><span style="">.</span><span class="colour" style="color:rgb(112, 61, 170)">Element</span><span style=""></span><span class="colour" style="color:rgb(187, 44, 162)">throws</span><span style=""> -> </span><span class="colour" style="color:rgb(112, 61, 170)">Bool</span><span style="">) </span><span class="colour" style="color:rgb(187, 44, 162)">rethrows</span><span style=""> -> </span><span class="colour" style="color:rgb(79, 129, 135)">Self</span><span style="">.</span><span class="colour" style="color:rgb(112, 61, 170)">Generator</span><span style="">.</span><span class="colour" style="color:rgb(112, 61, 170)">Element</span><span style="">? {</span><br></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span style=""></span><span class="colour" style="color:rgb(187, 44, 162)">for</span><span style=""> element </span><span class="colour" style="color:rgb(187, 44, 162)">in</span><span style=""></span><span class="colour" style="color:rgb(187, 44, 162)">self</span><span style=""></span><span class="colour" style="color:rgb(187, 44, 162)">where</span><span style=""></span><span class="colour" style="color:rgb(187, 44, 162)">try</span><span style=""> predicate(element) {</span><br></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span style=""></span><span class="colour" style="color:rgb(187, 44, 162)">return</span><span style=""> element</span><br></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span style=""> }</span><br></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(187, 44, 162);"><span class="colour" style="color:rgb(0, 0, 0)"></span><span style="">return</span><span class="colour" style="color:rgb(0, 0, 0)"></span><span style="">nil</span><br></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span style="">}</span><br></div>
</div>
<div> </div>
<div> </div>
<div>Also, I’d like suggest adding a variant that works better with heterogenous sequences, but I’ll raise that when this proposal goes into review.<br></div>
<div> </div>
<div>FYI: That variant would look like this:<br></div>
<div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span class="colour" style="color:rgb(187, 44, 162)">func</span><span style=""> find<T>(</span><span class="colour" style="color:rgb(187, 44, 162)">_</span><span style="">: </span><span class="colour" style="color:rgb(79, 129, 135)">T</span><span style="">.Type, </span><span class="colour" style="color:rgb(187, 44, 162)">@noescape</span><span style=""> matching predicate: </span><span class="colour" style="color:rgb(79, 129, 135)">T</span><span style=""></span><span class="colour" style="color:rgb(187, 44, 162)">throws</span><span style=""> -> </span><span class="colour" style="color:rgb(112, 61, 170)">Bool</span><span style="">) </span><span class="colour" style="color:rgb(187, 44, 162)">rethrows</span><span style=""> -> </span><span class="colour" style="color:rgb(79, 129, 135)">T</span><span style="">?</span><br></div>
</div>
<div> </div>
<div>A question by me on the swift-users mailing list describes its intention, implementation, and usage:<br></div>
<div><a href="https://lists.swift.org/pipermail/swift-users/Week-of-Mon-20160118/000893.html">[swift-users] Which is the more idiomatic approach for pinning down the type of a generic parameter?</a><br></div>
<div> </div>
<div>Cheers,<br></div>
<div> </div>
<div>Marco<br></div>
<div> </div>
<div> </div>
<div><blockquote type="cite"><div>On 2016-01-10, at 01:58, Kevin Ballard via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br></div>
<div> </div>
<div><div><div>Proposal PR submitted as <a href="https://github.com/apple/swift-evolution/pull/94">https://github.com/apple/swift-evolution/pull/94</a><br></div>
<div> </div>
<div>-Kevin Ballard<br></div>
<div> </div>
<div>On Tue, Dec 29, 2015, at 06:38 PM, Kevin Ballard wrote:<br></div>
<blockquote type="cite"><div>I'm proposing a new extension method on SequenceType called find(). It's similar to CollectionType.indexOf() except it returns the element:<br></div>
<div> </div>
<div><div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(112, 61, 170);"><span class="colour" style="color:rgb(187, 44, 162)">extension</span><span style=""></span>SequenceType<span style=""> {</span><br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(144, 45, 208);"><span style=""></span>/// Returns the first element where `predicate` returns `true`, or `nil`<br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(144, 45, 208);"><span style=""></span>/// if such value is not found.<br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span class="colour" style="color:rgb(187, 44, 162)">public</span> <span class="colour" style="color:rgb(187, 44, 162)">func</span> find(<span class="colour" style="color:rgb(187, 44, 162)">@noescape</span> predicate: (<span class="colour" style="color:rgb(187, 44, 162)">Self</span>.Generator.Element) <span class="colour" style="color:rgb(187, 44, 162)">throws</span> -> <span class="colour" style="color:rgb(112, 61, 170)">Bool</span>) <span class="colour" style="color:rgb(187, 44, 162)">rethrows</span> -> <span class="colour" style="color:rgb(112, 61, 170)">Self</span>.<span class="colour" style="color:rgb(112, 61, 170)">Generator</span>.<span class="colour" style="color:rgb(112, 61, 170)">Element</span>? {<br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span class="colour" style="color:rgb(187, 44, 162)">for</span> elt <span class="colour" style="color:rgb(187, 44, 162)">in</span> <span class="colour" style="color:rgb(187, 44, 162)">self</span> {<br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span class="colour" style="color:rgb(187, 44, 162)">if</span> <span class="colour" style="color:rgb(187, 44, 162)">try</span> predicate(elt) {<br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span class="colour" style="color:rgb(187, 44, 162)">return</span> elt<br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;"> }<br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;"> }<br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;"><span class="colour" style="color:rgb(187, 44, 162)">return</span> <span class="colour" style="color:rgb(187, 44, 162)">nil</span><br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;"> }<br></div>
<div style="margin-top:0px;margin-bottom:0px;font-size:11px;line-height:normal;font-family:Menlo;">}<br></div>
<div> </div>
<div>-Kevin Ballard<br></div>
</div>
<div> </div>
</blockquote><div> </div>
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