<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 Jun 28, 2017, at 6:32 PM, Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" class="">xiaodi.wu@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span 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; float: none; display: inline !important;" class=""><span class="Apple-converted-space"> </span>the reason why a function would return nil _are intended to be obvious, per the design rationale given in Swift project documents_.</span></div></blockquote></div><br class=""><div class="">The reason .last returns nil is obvious. But it doesn’t tell you anything about why the array itself should be non-empty at this point in the code.</div><div class=""><br class=""></div><div class=""><blockquote type="cite" class=""><span class="" style="display: inline !important;">I do not believe that "array must not be empty" or "array guaranteed non-empty" is such an example, and I cannot myself imagine another scenario where it would make such a difference.</span></blockquote></div><div class=""><span class="" style="display: inline !important;"><br class=""></span></div><div class=""><span class="" style="display: inline !important;">As the screener of a non-zero number of radars resulting from unwrapped nils, I would certainly appreciate more use of guard let x = x else { fatalError(“explanation”) } and hope that !! would encourage it.</span></div><div class=""><span class="" style="display: inline !important;"><br class=""></span></div><div class=""><span class="" style="display: inline !important;"><br class=""></span></div></body></html>