<div dir="ltr"><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">Swift-Evolution,</div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)"><br></div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">I propose that `clamp(to:)` be added to the standard library as detailed </div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">in the proposal written below. </div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">There is also an open pull request to the swift-evolution repository open here:</div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)"><br></div><div class="gmail_default"><font color="#274e13" face="comic sans ms, sans-serif"><a href="https://github.com/apple/swift-evolution/pull/641">https://github.com/apple/swift-evolution/pull/641</a></font><br></div><div class="gmail_default"><font color="#274e13" face="comic sans ms, sans-serif"><br></font></div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">The idea was discussed on previous threads and a few people helped make</div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">the draft proposal better. </div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">Since the reception of the idea was overall good, I thought it might be worth it </div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">to formally propose the idea. </div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)"><br></div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">Please tell me what you think.</div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)"><br></div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)">- Nick </div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)"><br></div><div class="gmail_default" style="font-family:"comic sans ms",sans-serif;color:rgb(39,78,19)"><h1 style="box-sizing:border-box;margin:0px 0px 16px;line-height:1.25;padding-bottom:0.3em;border-bottom:1px solid rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol"">Add clamp(to:) to the stdlib</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,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px"><li style="box-sizing:border-box">Proposal: <a href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/NNNN-filename.md" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none">SE-NNNN</a></li><li style="box-sizing:border-box;margin-top:0.25em">Authors: <a href="https://github.com/Nirma" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none">Nicholas Maccharoli</a></li><li style="box-sizing:border-box;margin-top:0.25em">Review Manager: TBD</li><li style="box-sizing:border-box;margin-top:0.25em">Status: <span style="box-sizing:border-box;font-weight:600">Awaiting review</span></li></ul><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px"><em style="box-sizing:border-box">During the review process, add the following fields as needed:</em></p><ul style="box-sizing:border-box;padding-left:2em;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px"><li style="box-sizing:border-box">Decision Notes: <a href="https://lists.swift.org/pipermail/swift-evolution/" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none">Rationale</a>, <a href="https://lists.swift.org/pipermail/swift-evolution/" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none">Additional Commentary</a></li><li style="box-sizing:border-box;margin-top:0.25em">Bugs: <a href="https://bugs.swift.org/browse/SR-NNNN" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none">SR-NNNN</a>, <a href="https://bugs.swift.org/browse/SR-MMMM" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none">SR-MMMM</a></li><li style="box-sizing:border-box;margin-top:0.25em">Previous Revision: <a href="https://github.com/apple/swift-evolution/blob/...commit-ID.../proposals/NNNN-filename.md" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none">1</a></li><li style="box-sizing:border-box;margin-top:0.25em">Previous Proposal: <a href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/XXXX-filename.md" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none">SE-XXXX</a></li></ul><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom:1px solid rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol""><a id="gmail-user-content-introduction" class="gmail-anchor" href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/NNNN-add-clamp-function.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"></a>Introduction</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">This proposal aims to add functionality to the standard library for clamping a value to a provided <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Range</code>. The proposed function would allow the user to specify a range to clamp a value to where if the value fell within the range, the value would be returned as is, if the value being clamped exceeded the upper or lower bound in value the value of the boundary the value exceeded would be returned.</p><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">Swift-evolution thread: <a href="https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20170306/thread.html#33674" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none">Add a <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamp</code> function to Algorithm.swift</a></p><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom:1px solid rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol""><a id="gmail-user-content-motivation" class="gmail-anchor" href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/NNNN-add-clamp-function.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"></a>Motivation</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">There have been quite a few times in my professional and personal programming life where I reached for a function to limit a value to a given range and was disappointed it was not part of the standard library.</p><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">There already exists an extension to <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">CountableRange</code> in the standard library implementing <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> that will limit the calling range to that of the provided range, so having the same functionality but just for types that conform to the <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Comparable</code> protocol would be conceptually consistent.</p><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">Having functionality like <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> added to <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Comparable</code> as a protocol extension would benefit users of the Swift language who wish to guarantee that a value is kept within bounds, perhaps one example of this coming in handy would be to limit the result of some calculation between two acceptable numerical limits, say the bounds of a coordinate system.</p><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom:1px solid rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol""><a id="gmail-user-content-proposed-solution" class="gmail-anchor" href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/NNNN-add-clamp-function.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"></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,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">The proposed solution is to add a <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> function to the Swift Standard Library as an extension to <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Comparable</code> and <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Strideable</code>. The function would return a value within the bounds of the provided range, if the value <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> is being called on falls within the provided range then the original value would be returned. If the value was less or greater than the bounds of the provided range then the respective lower or upper bound of the range would be returned.</p><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">It does not make sense to call <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> with an empty range, therefore calling <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> and passing an empty range like <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">foo.clamped(to: 0..<0)</code> would result in a fatal error.</p><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">Given a <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> function existed it could be called in the following way, yielding the results in the adjacent comments:</p><div class="gmail-highlight gmail-highlight-source-swift" style="box-sizing:border-box;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px"><pre style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;margin-top:0px;margin-bottom:0px;font-stretch:normal;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(246,248,250);border-radius:3px;word-break:normal"><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">let</span> foo <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">=</span> <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">100</span>
<span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="gmail-pl-c" style="box-sizing:border-box">//</span> Closed range variant</span>
<span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"></span>
foo.<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">clamped</span>(<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">to</span>: <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">0</span><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">...</span><span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">50</span>) <span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="gmail-pl-c" style="box-sizing:border-box">//</span> 50</span>
<span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"></span>foo.<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">clamped</span>(<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">to</span>: <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">200</span><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">...</span><span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">300</span>) <span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="gmail-pl-c" style="box-sizing:border-box">//</span> 200</span>
<span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"></span>foo.<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">clamped</span>(<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">to</span>: <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">0</span><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">...</span><span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">150</span>) <span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="gmail-pl-c" style="box-sizing:border-box">//</span> 100</span>
<span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"></span>
<span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="gmail-pl-c" style="box-sizing:border-box">//</span> Half-Open range variant</span>
<span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"></span>
foo.<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">clamped</span>(<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">to</span>: <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">0</span><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">..<</span><span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">50</span>) <span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="gmail-pl-c" style="box-sizing:border-box">//</span> 49</span>
<span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"></span>foo.<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">clamped</span>(<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">to</span>: <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">200</span><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">..<</span><span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">300</span>) <span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="gmail-pl-c" style="box-sizing:border-box">//</span> 200</span>
<span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"></span>foo.<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">clamped</span>(<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">to</span>: <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">0</span><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">..<</span><span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">150</span>) <span class="gmail-pl-c" style="box-sizing:border-box;color:rgb(150,152,150)"><span class="gmail-pl-c" style="box-sizing:border-box">//</span> 100</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:1px solid rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol""><a id="gmail-user-content-detailed-design" class="gmail-anchor" href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/NNNN-add-clamp-function.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"></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,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">The implementation of <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> that is being proposed is composed of two protocol extensions; one protocol extension on <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Comparable</code> and another on <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Strideable</code>.</p><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">The implementation for <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> as an extension to <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Comparable</code> accepting a range of type <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">ClosedRange<Self></code>would look like the following:</p><div class="gmail-highlight gmail-highlight-source-swift" style="box-sizing:border-box;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px"><pre style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;margin-top:0px;margin-bottom:0px;font-stretch:normal;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(246,248,250);border-radius:3px;word-break:normal"><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">extension</span> <span class="gmail-pl-en" style="box-sizing:border-box;color:rgb(121,93,163)"><span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Comparable</span></span> {
<span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">func</span> <span class="gmail-pl-en" style="box-sizing:border-box;color:rgb(121,93,163)">clamped</span>(<span class="gmail-pl-en" style="box-sizing:border-box;color:rgb(121,93,163)">to</span> <span class="gmail-pl-smi" style="box-sizing:border-box;color:rgb(51,51,51)">range</span>: <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">ClosedRange</span><<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Self</span>>) <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">-></span> <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Self</span> {
<span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">if</span> <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">self</span> <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">></span> range.<span class="gmail-pl-smi" style="box-sizing:border-box;color:rgb(51,51,51)">upperBound</span> {
<span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">return</span> range.<span class="gmail-pl-smi" style="box-sizing:border-box;color:rgb(51,51,51)">upperBound</span>
} <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">else</span> <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">if</span> <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">self</span> <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)"><</span> range.<span class="gmail-pl-smi" style="box-sizing:border-box;color:rgb(51,51,51)">lowerBound</span> {
<span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">return</span> range.<span class="gmail-pl-smi" style="box-sizing:border-box;color:rgb(51,51,51)">lowerBound</span>
} <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">else</span> {
<span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">return</span> <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">self</span>
}
}
}</pre></div><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">The implementation of <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">clamped(to:)</code> as an extension on <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Strideable</code> would be confined to cases where the stride is of type <code style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;padding:0.2em 0px;margin:0px;background-color:rgba(27,31,35,0.0470588);border-radius:3px">Integer</code>. The implementation would be as follows:</p><div class="gmail-highlight gmail-highlight-source-swift" style="box-sizing:border-box;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px"><pre style="box-sizing:border-box;font-family:sfmono-regular,consolas,"liberation mono",menlo,courier,monospace;font-size:13.6px;margin-top:0px;margin-bottom:0px;font-stretch:normal;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(246,248,250);border-radius:3px;word-break:normal"><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">extension</span> <span class="gmail-pl-en" style="box-sizing:border-box;color:rgb(121,93,163)"><span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Strideable</span></span> <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">where</span> <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Stride</span><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">:</span> <span class="gmail-pl-e" style="box-sizing:border-box;color:rgb(121,93,163)"><span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Integer</span></span> {
<span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">func</span> <span class="gmail-pl-en" style="box-sizing:border-box;color:rgb(121,93,163)">clamped</span>(<span class="gmail-pl-en" style="box-sizing:border-box;color:rgb(121,93,163)">to</span> <span class="gmail-pl-smi" style="box-sizing:border-box;color:rgb(51,51,51)">range</span>: <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Range</span><<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Self</span>>) <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">-></span> <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">Self</span> {
<span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">guard</span> <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">!</span>range.<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">isEmpty</span> { <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">fatalError</span>(<span class="gmail-pl-s" style="box-sizing:border-box;color:rgb(24,54,145)"><span class="gmail-pl-pds" style="box-sizing:border-box">"</span>Can not clamp to an empty range.<span class="gmail-pl-pds" style="box-sizing:border-box">"</span></span>) }
<span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">return</span> <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">clamped</span>(<span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">to</span>: range.<span class="gmail-pl-smi" style="box-sizing:border-box;color:rgb(51,51,51)">lowerBound</span><span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">...</span>(range.<span class="gmail-pl-smi" style="box-sizing:border-box;color:rgb(51,51,51)">upperBound</span> <span class="gmail-pl-k" style="box-sizing:border-box;color:rgb(167,29,93)">-</span> <span class="gmail-pl-c1" style="box-sizing:border-box;color:rgb(0,134,179)">1</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:1px solid rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol""><a id="gmail-user-content-source-compatibility" class="gmail-anchor" href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/NNNN-add-clamp-function.md#source-compatibility" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none;float:left;padding-right:4px;line-height:1"></a>Source compatibility</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">This feature is purely additive; it has no effect on source compatibility.</p><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom:1px solid rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol""><a id="gmail-user-content-effect-on-abi-stability" class="gmail-anchor" href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/NNNN-add-clamp-function.md#effect-on-abi-stability" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none;float:left;padding-right:4px;line-height:1"></a>Effect on ABI stability</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">This feature is purely additive; it has no effect on ABI stability.</p><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom:1px solid rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol""><a id="gmail-user-content-effect-on-api-resilience" class="gmail-anchor" href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/NNNN-add-clamp-function.md#effect-on-api-resilience" style="box-sizing:border-box;background-color:transparent;color:rgb(3,102,214);text-decoration:none;float:left;padding-right:4px;line-height:1"></a>Effect on API resilience</h2><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px">The proposed function would become part of the API but purely additive.</p><h2 style="box-sizing:border-box;margin-top:24px;margin-bottom:16px;line-height:1.25;padding-bottom:0.3em;border-bottom:1px solid rgb(234,236,239);color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol""><a id="gmail-user-content-alternatives-considered" class="gmail-anchor" href="https://github.com/Nirma/swift-evolution/blob/2ecfd45f4636e44f1000177fa509b1412cebef92/proposals/NNNN-add-clamp-function.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"></a>Alternatives considered</h2><p style="box-sizing:border-box;margin-top:0px;color:rgb(36,41,46);font-family:-apple-system,system-ui,"segoe ui",helvetica,arial,sans-serif,"apple color emoji","segoe ui emoji","segoe ui symbol";font-size:16px;margin-bottom:0px">Aside from doing nothing, no other alternatives were considered.</p></div></div>