<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><blockquote type="cite" class=""><div class="">On 13 Dec 2015, at 05:54, Paul Ossenbruggen 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=""><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;">Hello All, </div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;"><br class=""></div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;">Been sick in bed all day, but decided to try to be productive…</div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;"><br class=""></div><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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="">I did a rough draft of a proposal for implementing if expressions and switch expressions based upon the discussions we had here. I have tried to keep the scope of the changes as small as possible, only added one keyword and kept things as similar to the existing language constructs as possible. If anyone wants to help me with this, or has feedback, please let me know,</span><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;"><br class=""></div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;"><a href="https://github.com/possen/swift-evolution/blob/master/0020.md" class="">https://github.com/possen/swift-evolution/blob/master/0020.md</a></div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;"><br class=""></div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;">Thanks,</div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;">- Paul</div></div></blockquote></div><br class=""><div class=""><br class=""></div><div class="">Thanks for taking the time to put this detailed proposal together.</div><div class=""><br class=""></div><div class="">Regarding the if…then…else expression, it all looks good to me. </div><div class="">I have a few comments on the proposed switch expression:</div><div class=""><br class=""></div><div class="">1)</div><div class="">Is it worth reusing the ‘then’ keyword, instead of colon? If a new keyword is to be added, it’d be good if it wasn’t restricted to only one use. The advantage of using ‘then’ in switch would be to further distinguish the expression from the statement and would fit with the if…then…else expression. The disadvantage is that it adds a little more verbosity (ideally, expressions should be syntactically light-weight).</div><div class=""><br class=""></div><div class="">2)</div><div class="">Having the ‘case’ keyword appear only once, looks a bit odd to me, it gives the impression that it is only associated with the first case.</div><div class="">My preference would be to omit the ‘case’ keyword entirely. In the switch statement it can be helpful, as the cases can run over several lines, therefore the keyword is a handy visual marker for the different cases. The expression for each case should only be one line, so this visual marker shouldn’t be required for switch expressions. Having said that, I understand if people think this is too much of a change. Therefore my suggestion is, either the ‘case’ keyword is omitted from the expression, or it is associated with every case as it currently is with the switch statement.</div><div class=""><br class=""></div><div class="">3)</div><div class="">It might be worth showing an example of binding to associated values in a enum using a switch expression? However, the behaviour should be identical to the switch statement, so this might not be required.</div><div class=""><br class=""></div><div class="">Al</div><div class=""><br class=""></div></body></html>