<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Jan 17, 2017, at 9:33 PM, David Sweeris via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; 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-stroke-width: 0px;" class=""><br class="Apple-interchange-newline">On Jan 17, 2017, at 22:30, Braeden Profile via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""></div><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; 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;" class="">Hello Swift Community!<div class=""><br class=""></div><div class="">I know that I’ve seen this mentioned before, but what with Enhanced Existentials being brought up, I think this is worth mentioning now. What is the plan regarding letting existentials conform to their protocols? Currently, in Swift 3, it is impossible to write code like this:</div><div class=""><pre class="" style="font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 0.94em; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); border: 1px solid rgb(204, 204, 204); white-space: pre-wrap; word-wrap: break-word; padding: 5px;"><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 142, 1);">protocol</span><span class="" style="font-variant-ligatures: no-common-ligatures;"> Updatable</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;"><span class="Apple-tab-span" style="white-space: pre;"> </span>{ </span><span class="" style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 142, 1);">func</span><span class="" style="font-variant-ligatures: no-common-ligatures;"> update() }</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;"><span class="" style="font-variant-ligatures: no-common-ligatures;"></span><br class=""></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 142, 1);">struct</span><span class="" style="font-variant-ligatures: no-common-ligatures;"> UpdatePool<T: Updatable></span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(146, 146, 146);"><span class="" style="font-variant-ligatures: no-common-ligatures;"><span class="Apple-tab-span" style="white-space: pre;"> </span>{ </span><span class="" style="font-variant-ligatures: no-common-ligatures;">/* ... */</span><span class="" style="font-variant-ligatures: no-common-ligatures;"> }</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;"><span class="" style="font-variant-ligatures: no-common-ligatures;"></span><br class=""></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 142, 1);">let</span><span class="" style="font-variant-ligatures: no-common-ligatures;"> heterogenousPool = </span><span class="" style="font-variant-ligatures: no-common-ligatures; color: rgb(74, 134, 114);">UpdatePool</span><span class="" style="font-variant-ligatures: no-common-ligatures;"><</span><span class="" style="font-variant-ligatures: no-common-ligatures; color: rgb(94, 174, 174);">Updatable</span><span class="" style="font-variant-ligatures: no-common-ligatures;">>()</span></div></pre><div class="">Error on the last line: “Using ‘Updatable’ as a concrete type conforming to protocol ‘Updatable’ is not supported.”</div></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Although my most common use case of this behavior has actually been solved (using ‘AnyObject’ as a concrete type conforming to ‘AnyObject’), I wonder why this can’t be extended to any protocol existential (a field which is about to explode, if we succeed in Enhancing them).</div><div class=""><br class=""></div><div class="">What do you guys think?</div></blockquote><br style="font-family: Helvetica; font-size: 12px; 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-stroke-width: 0px;" class=""><div style="font-family: Helvetica; font-size: 12px; 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-stroke-width: 0px;" class="">+1, but I<span class="Apple-converted-space"> </span><i class="">think</i><span class="Apple-converted-space"> </span>there's a compiler limitation preventing it at the moment.</div></div></blockquote><div><br class=""></div>See my recent post: <a href="https://www.mail-archive.com/swift-users@swift.org/msg03427.html" class="">https://www.mail-archive.com/swift-users@swift.org/msg03427.html</a></div><div><br class=""></div><div>Slava</div><div><br class=""></div><div><br class=""><blockquote type="cite" class=""><div class=""><div style="font-family: Helvetica; font-size: 12px; 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-stroke-width: 0px;" class=""><br class=""></div><div style="font-family: Helvetica; font-size: 12px; 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-stroke-width: 0px;" class="">- Dave Sweeris </div><span style="font-family: Helvetica; font-size: 12px; 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-stroke-width: 0px; float: none; display: inline !important;" class="">_______________________________________________</span><br style="font-family: Helvetica; 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