<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Jul 10, 2017, at 5:16 PM, William Shipley via swift-evolution &lt;<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>&gt; wrote:</div><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="margin: 0px; line-height: normal; background-color: rgb(255, 255, 255);" class=""><div class=""><br class=""></div><div class="">(Note the horrible hack on&nbsp;KeyedEncodingContainer where I had to special-case arrays of &lt;Equatable&gt;s, I guess because the compiler doesn’t know an array of &lt;Equatable&gt;s is Equatable itself?)</div></div></div></div></blockquote><br class=""></div><div>Correct. Swift does not yet have the necessary language machinery to express "Array&lt;T&gt; is Equatable whenever T is Equatable".&nbsp;</div><div><br class=""></div><div>SE-0143 "Conditional conformances" is approved but not yet implemented.</div><div><a href="https://github.com/apple/swift-evolution/blob/master/proposals/0143-conditional-conformances.md" class="">https://github.com/apple/swift-evolution/blob/master/proposals/0143-conditional-conformances.md</a></div><div><br class=""></div><br class=""><div class="">--&nbsp;</div><div class="">Greg Parker &nbsp; &nbsp; <a href="mailto:gparker@apple.com" class="">gparker@apple.com</a>&nbsp; &nbsp; &nbsp;Runtime Wrangler</div><div class=""><br class=""></div><div class=""><br class=""></div></body></html>