<div dir="ltr"><div>This could work, but you’re also giving up all the nice Numeric and FloatingPoint conformances when you use this,, all of a sudden adding two angles together isn’t let <span style="font-family:monospace,monospace">γ = α + β</span>, it’s <span style="font-family:monospace,monospace">γ = Angle.radians(α.radians + β.radians)</span>. just no. at the risk of blowing up the scope of this idea, dedicated <span style="font-family:monospace,monospace">Angle</span> types also begs for generic trigonometric functions like <span style="font-family:monospace,monospace">Angle.sin(_:)</span> and <span style="font-family:monospace,monospace">Angle.cos(_:)</span>. i proposed that a while back and even tried implementing it but fast trig evaluation doesn’t genericize well since it relies a lot on <span style="font-family:monospace,monospace">rsqrt</span>-style magic constants<br><br></div>also, why are <span style="font-family:monospace,monospace">radians(_:)</span> and <span style="font-family:monospace,monospace">degrees(_:)</span> static functions? i really only use static constructors for initializers that have side effects<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Jan 14, 2018 at 6:36 AM, Karl Wagner <span dir="ltr">&lt;<a href="mailto:razielim@gmail.com" target="_blank">razielim@gmail.com</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word;line-break:after-white-space"><br><div><span class=""><br><blockquote type="cite"><div>On 14. Jan 2018, at 09:51, Taylor Swift via swift-evolution &lt;<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>&gt; wrote:</div><br class="m_-671662914338481272Apple-interchange-newline"><div><div dir="auto"><div></div><div>I do a lot of geometry and spherical-related work and i have never found an Angle type to be worth having. Always use radians. It’s what sin() and cos() take, it’s what graphics APIs like Cairo expect, it’s what graphics formats like SVG use. plus,, do you *really* want to be case-branching on every angle value? that really adds up when you’re converting 100,000s of lat-long pairs to cartesian.</div></div></div></blockquote><div><br></div></span><div>You can do it without case-branching. I too have an Angle type; this is what I use:</div><div><br></div><div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)"><span style="color:#e12da0">public</span> <span style="color:#e12da0">struct</span> Angle&lt;T: <span style="color:#29a09f">FloatingPoint</span>&gt; {</div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">  <span style="color:#e12da0">public</span> <span style="color:#e12da0">var</span> radians: <span style="color:#18b5b1">T</span></div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">  <span style="color:#e12da0">public</span> <span style="color:#e12da0">var</span> degrees: <span style="color:#18b5b1">T</span> {</div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">    <span style="color:#e12da0">return</span> (<span style="color:#18b5b1">radians</span> / .<span style="color:#29a09f">pi</span>) * <span style="color:#00aaa3">180</span></div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">  }</div><div style="margin:0px;font-stretch:normal;line-height:normal;background-color:rgb(41,43,54);min-height:14px"><br></div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">  <span style="color:#e12da0">public</span> <span style="color:#e12da0">static</span> <span style="color:#e12da0">func</span> radians(<span style="color:#e12da0">_</span> rads: <span style="color:#18b5b1">T</span>) -&gt; <span style="color:#18b5b1">Angle</span> {</div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">    <span style="color:#e12da0">return</span> <span style="color:#18b5b1">Angle</span>(radians: rads)</div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">  }</div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">  <span style="color:#e12da0">public</span> <span style="color:#e12da0">static</span> <span style="color:#e12da0">func</span> degrees(<span style="color:#e12da0">_</span> degs: <span style="color:#18b5b1">T</span>) -&gt; <span style="color:#18b5b1">Angle</span> {</div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">    <span style="color:#e12da0">return</span> <span style="color:#18b5b1">Angle</span>(radians: (degs / <span style="color:#00aaa3">180</span>) * .<span style="color:#29a09f">pi</span>)</div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">  }</div><div style="margin:0px;font-stretch:normal;font-size:16px;line-height:normal;font-family:&quot;Fira Code&quot;;color:rgb(231,232,235);background-color:rgb(41,43,54)">}</div></div><div><br></div>If you ask for “radians” (like most low-level trig code will), you just get the stored property. The conversion “overhead” is only done at construction time, so it makes a convenient parameter/return value.</div><span class="HOEnZb"><font color="#888888"><div><br></div><div>- Karl</div></font></span><div><div class="h5"><div><br><blockquote type="cite"><div><div dir="auto"><div><br>On Jan 14, 2018, at 12:04 AM, BJ Homer via swift-evolution &lt;<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>&gt; wrote:<br><br></div><blockquote type="cite"><div>An Angle type already exists in Foundation; see Measurement&lt;UnitAngle&gt;. You could add some convenience methods in an extension pretty easily.<div><br></div><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)"><span style="color:#ba2da2">import</span> Foundation</div></div><div><div style="margin:0px;font-stretch:normal;font-size:12px;line-height:normal;background-color:rgb(255,255,255);min-height:14px"><br></div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(112,61,170);background-color:rgb(255,255,255)"><span style="color:#ba2da2">typealias</span><span> Angle = </span>Measurement<span>&lt;</span>UnitAngle<span>&gt;</span></div></div><div><div style="margin:0px;font-stretch:normal;font-size:12px;line-height:normal;background-color:rgb(255,255,255);min-height:14px"><br></div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)"><span style="color:#ba2da2">extension</span> <span style="color:#703daa">Measurement</span> <span style="color:#ba2da2">where</span> UnitType == UnitAngle {</div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)">    <span style="color:#ba2da2">var</span> sine: <span style="color:#703daa">Double</span> {</div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)">        <span style="color:#ba2da2">let</span> radians = <span style="color:#ba2da2">self</span>.<span style="color:#3e1e81">converted</span>(to: .<span style="color:#703daa">radians</span>).<span style="color:#703daa">value</span></div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)">        <span style="color:#ba2da2">return</span> <span style="color:#3e1e81">sin</span>(radians)</div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)">    }</div></div><div><p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255);min-height:13px">    <br class="m_-671662914338481272webkit-block-placeholder"></p></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)">    <span style="color:#ba2da2">static</span> <span style="color:#ba2da2">var</span> threeQuarterTurn: <span style="color:#4f8187">Angle</span> {</div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)">        <span style="color:#ba2da2">return</span> <span style="color:#4f8187">Angle</span>(value: <span style="color:#272ad8">0.75</span>, unit: .<span style="color:#703daa">revolutions</span>)</div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)">    }</div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;background-color:rgb(255,255,255)">}</div></div><div><div style="margin:0px;font-stretch:normal;font-size:12px;line-height:normal;background-color:rgb(255,255,255);min-height:14px"><br></div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(79,129,135);background-color:rgb(255,255,255)"><span style="color:#ba2da2">let</span><span> x = </span>Angle<span>.</span>threeQuarterTurn</div></div><div><div style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(79,129,135);background-color:rgb(255,255,255)">x<span>.</span>sine<span> </span><span style="color:#008400">// -1</span></div></div></blockquote><div><div><br></div><div>-BJ</div><div><br></div><div><br><blockquote type="cite"><div>On Jan 13, 2018, at 9:31 PM, Erica Sadun via swift-evolution &lt;<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>&gt; wrote:</div><br class="m_-671662914338481272Apple-interchange-newline"><div><div style="word-wrap:break-word;line-break:after-white-space">I would like to see a full Geometry implementation but I don&#39;t think it should be part of the standard library.<div><br></div><div>I&#39;ve kicked around some ideas here: </div><div><br></div><div>* <a href="https://gist.github.com/erica/8cb4b21cf0c429828fad1d8ad459b71b" target="_blank">https://gist.github.com/<wbr>erica/<wbr>8cb4b21cf0c429828fad1d8ad459b7<wbr>1b</a></div><div>* <a href="https://gist.github.com/erica/ee06008202c9fed699bfa6254c42c721" target="_blank">https://gist.github.com/<wbr>erica/<wbr>ee06008202c9fed699bfa6254c42c7<wbr>21</a></div><div><br></div><div>and</div><div><br></div><div>* <a href="https://github.com/erica/SwiftGeometry" target="_blank">https://github.com/erica/<wbr>SwiftGeometry</a><br><div><br><blockquote type="cite"><div>On Jan 13, 2018, at 7:49 PM, Jonathan Hull via swift-evolution &lt;<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>&gt; wrote:</div><br class="m_-671662914338481272Apple-interchange-newline"><div><div style="word-wrap:break-word">Hi Evolution,<div><br></div><div>I would <i>really</i> like to see Swift gain an Angle type in the standard library.  Every time I have to deal with an angle in an api, I have to go figure out the conventions for that call.  Is it in degrees? Is it in radians?  What if it is in radians, but I want to think about it in degrees?</div><div><br></div><div>I ended up writing an Angle type for my own code a few years back, and I have to say it is really wonderful.  It has greatly simplified my graphics work.  It takes a lot of mental load off of my brain when dealing with Angles.</div><div><br></div><div>I can of course initialize it either as degrees or radians (or revolutions), but I can also just say things like ‘.threeQuarterTurn’, and then I can get the value back out in whatever format I like.  There are also useful additions that let me normalize the angle to different ranges and which let me snap to the nearest multiple of an angle. Both of these are enormously useful for user facing features.  I can also do math on angles in a way that makes geometric sense for angles.  It is also really useful for interacting with CGVectors in intelligent ways.</div><div><br></div><div>Using Doubles or CGFloats to represent angles everywhere is just semantically wrong IMHO, and it stops us from adding all of these angle-specific niceties.</div><div><br></div><div>Happy to provide code if there is interest…</div><div><br></div><div>Thanks,</div><div>Jon</div></div>______________________________<wbr>_________________<br>swift-evolution mailing list<br><a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a><br><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank">https://lists.swift.org/<wbr>mailman/listinfo/swift-<wbr>evolution</a><br></div></blockquote></div><br></div></div>______________________________<wbr>_________________<br>swift-evolution mailing list<br><a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a><br><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank">https://lists.swift.org/<wbr>mailman/listinfo/swift-<wbr>evolution</a><br></div></blockquote></div><br></div></div></blockquote><blockquote type="cite"><div><span>______________________________<wbr>_________________</span><br><span>swift-evolution mailing list</span><br><span><a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a></span><br><span><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank">https://lists.swift.org/<wbr>mailman/listinfo/swift-<wbr>evolution</a></span><br></div></blockquote></div>______________________________<wbr>_________________<br>swift-evolution mailing list<br><a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a><br><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank">https://lists.swift.org/<wbr>mailman/listinfo/swift-<wbr>evolution</a><br></div></blockquote></div><br></div></div></div></blockquote></div><br></div>