<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><br class=""><blockquote type="cite" class=""><div class="">On Nov 21, 2017, at 9:21 PM, Chris Lattner <<a href="mailto:clattner@nondot.org" class="">clattner@nondot.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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class="Apple-interchange-newline"><br class=""><blockquote type="cite" class=""><div class="">On Nov 21, 2017, at 7:19 PM, Douglas Gregor 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 dir="auto" class=""><br class=""><br class=""><div class="">Sent from my iPhone</div><div class=""><br class="">On Nov 21, 2017, at 3:46 PM, Tony Allevato <<a href="mailto:tony.allevato@gmail.com" class="">tony.allevato@gmail.com</a>> wrote:<br class=""><br class=""></div><blockquote type="cite" class=""><div class="">Does that mean that once structural types can conform to protocols, would the core team want to remove Optional as a nominal type and just use “T?”?<span class="Apple-converted-space"> </span></div></blockquote><div class=""><br class=""></div><div class="">Yes; at least, it’s a direction we’ve discussed a number of times. </div><br class=""><blockquote type="cite" class=""><div class="">Or has that ship sailed because of source compatibility and you just don’t want to introduce any new nominals that shadow structurals?<br class=""></div></blockquote><div class=""><br class=""></div>typealias Optional<T> = T?<div class=""><br class=""></div><div class="">Should address source compatibility. </div></div></div></blockquote><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Or alternatively, one could decide to make the generics system *only and forever* work on nominal types, and make the syntactic sugar just be sugar for named types like Swift.Tuple, Function, and Optional. Either design could work.</div></div></blockquote><br class=""></div><div>We don’t have a way to make it work for function types, though, because of parameter-passing conventions. Well, assuming we don’t invent something that allows:</div><div><br class=""></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Function<Double, inout String></div><div><br class=""></div><div>to exist in the type system. Tuple labels have a similar problem.</div><div><br class=""></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- Doug</div><div><br class=""></div><br class=""></body></html>