<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 Aug 31, 2016, at 10:21 AM, Dan Loewenherz <<a href="mailto:dan@lionheartsw.com" class="">dan@lionheartsw.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="font-family: Alegreya-Regular; font-size: 15px; 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="">You'll need to specify a protocol where you're currently specifying "Bool". A generic constraint can't take a concrete type as an argument. </span></div></blockquote><br class=""></div><div>OK … this should be described in the book, though. (Any doc writers listening? Or is there a procedure for requesting improvements to the book?)</div><div><br class=""></div><div>I’m also bemused that (as I said) there is a boolean protocol in Swift 2.2, and a different one in master (according to <a href="http://swiftdoc.org" class="">swiftdoc.org</a>), but none in Swift 3.0 (as of Xcode 8 beta 6). Is this just a glitch that snuck into the release? Or does the Swift in Xcode predate an API freeze?</div><div><br class=""></div><div>—Jens</div></body></html>