<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></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 Dec 15, 2015, at 8:45 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=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">This one is tough. It is a very, very common user request and existentials are painfully under implemented in Swift. On the other hand, it's an additive feature that isn't likely (IMO!) to be important for ABI stabilization in the language or library. So, I would put it out of scope for Swift 3. </span></div></blockquote></div><br class=""><div class="">It could be important to stabilizing the standard library, since existentials ought to replace the ad-hoc type-erased AnySequence etc. wrappers that are currently hand-written in the standard library.</div><div class=""><br class=""></div><div class="">-Joe</div></body></html>