<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 Feb 1, 2017, at 3:13 PM, David Hart <<a href="mailto:david@hartbit.com" class="">david@hartbit.com</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="">Second question inline:</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=""><br class=""><div class=""><br class=""><br class="">Sent from my iPhone</div>On 1 Feb 2017, at 23:09, David Hart <<a href="mailto:david@hartbit.com" class="">david@hartbit.com</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=""><div class="">I did consider it, but didn’t want to put too much on your plate for Swift 4. But if you’re mentioning it, I’ll go ahead and add it to the second version of the proposal.<div class=""><br class=""></div><div class="">By the way, what you is your point of view about the discussions we’ve had concerning the positioning of the class constraint?</div><div class=""><br class=""></div><div class="">David.</div><div class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On 1 Feb 2017, at 22:58, Douglas Gregor <<a href="mailto:dgregor@apple.com" class="">dgregor@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="" applecontenteditable="true" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Jan 29, 2017, at 8:39 AM, David Hart <<a href="mailto:david@hartbit.com" class="">david@hartbit.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Hello,<div class=""><br class=""></div><div class="">As promised, I wrote the first draft of a proposal to add class requirements to the existential syntax. Please let me know what you think.</div><div class=""><br class=""></div><div class=""><a href="https://github.com/hartbit/swift-evolution/blob/subclass-existentials/proposals/XXXX-subclass-existentials.md" class="">https://github.com/hartbit/swift-evolution/blob/subclass-existentials/proposals/XXXX-subclass-existentials.md</a></div></div></div></blockquote><div class=""><br class=""></div><div class="">This looks good! I’m looking forward to the second draft, but I have one question.</div><div class=""><br class=""></div><div class="">Did you consider the generalized “class” constraint? IIRC, this was in Austin’s larger proposal, and it allowed for (e.g.)</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>typealias CustomStringConvertibleClass = class & CustomStringConvertible // class that conforms to CustomStringConvertible</div><div class=""><br class=""></div><div class="">and potentially a wonderful cleanup where AnyObject ceases to be a weird special protocol and instead becomes</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>typealias AnyObject = Any & class</div><div class=""><br class=""></div></div></div></div></blockquote></div></div></div></blockquote><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="">Austin's proposal defines it as:</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=""><span class="pl-k" style="background-color: rgba(255, 255, 255, 0); box-sizing: border-box;"><br class=""></span></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=""><span class="pl-k" style="background-color: rgba(255, 255, 255, 0); box-sizing: border-box;">typealias</span><span style="background-color: rgba(255, 255, 255, 0);" class=""><span class="Apple-converted-space"> </span></span><span class="pl-en" style="background-color: rgba(255, 255, 255, 0); box-sizing: border-box;">AnyObject</span><span style="background-color: rgba(255, 255, 255, 0);" class=""><span class="Apple-converted-space"> </span></span><span class="pl-k" style="background-color: rgba(255, 255, 255, 0); box-sizing: border-box;">=</span><span style="background-color: rgba(255, 255, 255, 0);" class=""><span class="Apple-converted-space"> </span>class</span></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=""><span style="background-color: rgba(255, 255, 255, 0);" class=""><br class=""></span></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=""><span style="background-color: rgba(255, 255, 255, 0);" class="">Is Any necessary?</span></div></div></blockquote><br class=""></div><div>Nah, it should be okay to just have “class” there.</div><div><br class=""></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- Doug</div><div><br class=""></div></body></html>