<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=""><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">Collections have mutating functions for removing the first and last element.</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">One of these is popLast(), which will safely check if the collection is empty before popping the last element.</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69); min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">So calling popLast() is like doing:<br class="">
if !collection.isEmpty {</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class=""><span class="Apple-tab-span" style="white-space:pre"> </span>collection.removeLast()</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">}</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69); min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">There also exists a popFirst() function, but what I find inconsistent is that popFirst() is only available on ArraySlice.</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69); min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">Example:<br class="">
var collection = [1, 2, 3, 4]</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">collection.removeFirst() // works fine</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">collection.removeLast() // works fine</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">let last = collection.popLast() // works fine</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">let first = collection.popFirst() // Compile error: [Int] is not convertible to 'ArraySlice<Int>'</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69); min-height: 14px;" class=""><br class=""></div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">Is it intended that popLast() is available on collections, but popFirst() is not?</div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class=""><br class=""></div><div style="margin: 0px; line-height: normal; font-family: 'Helvetica Neue'; color: rgb(69, 69, 69);" class="">– Louis D'hauwe</div></body></html>