<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 Jul 11, 2016, at 4:49 AM, Ross O'Brien <<a href="mailto:narrativium+swift@gmail.com" class="">narrativium+swift@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">I'm in favour of this concept being available in Swift, but it does need to make a clear distinction somewhere between a case which matches anything (and can catch any fallthrough/continue) and a case which matches none of the above. I don't know whether we need to introduce an explicit term for this, or whether we make this the distinction between 'case _:' and 'default:' (with the side-effect that we can now justify 'default' in the language).<div class=""><br class=""></div><div class="">For example: let's use this switch to play fizzbuzz.</div><div class=""><br class=""></div><div class="">switch value</div><div class="">{</div><div class=""> case x where x % 3 == 0:</div><div class=""> print("fizz")</div><div class=""> continue</div><div class=""> case x where x % 5 == 0:</div><div class=""> print("buzz")</div><div class=""> default:</div><div class=""> print(value)</div><div class="">}</div><div class=""><br class=""></div><div class="">I know this is a trivial example, but it's also a frequent example used to teach switch to programmers.</div><div class="">The keywords in play are 'continue' and 'default'. A multiple of 5 but not 3 will print 'buzz' and be done. A multiple of 3 and 5 will print 'fizz buzz'. Any number not a multiple of 3 or 5 will say its value. Crucially, a multiple of 3 but not 5 will say fizz, won't say buzz, and won't say the number itself - whereas if we used 'case _', it would say fizz and then the number itself.</div></div></div></blockquote><br class=""></div><div><br class=""></div><div>The standard question asks you to print the value and then fizz and/or buzz on the same line and then move to the next line.</div><div><br class=""></div><div>If you use the rules you stated ("Any number not a multiple of 3 or 5 will say its value."), it would look like this:</div><div><br class=""></div><div><span style="font-family: Menlo; font-size: 16px; font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">switch</span><span style="font-family: Menlo; font-size: 16px; font-variant-ligatures: no-common-ligatures;" class=""> value</span></div><div class=""><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">{</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">where</span><span style="font-variant-ligatures: no-common-ligatures" class=""> !(x % </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">5</span><span style="font-variant-ligatures: no-common-ligatures" class=""> == </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span><span style="font-variant-ligatures: no-common-ligatures" class=""> || x % </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">3</span><span style="font-variant-ligatures: no-common-ligatures" class=""> == </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span><span style="font-variant-ligatures: no-common-ligatures" class="">):</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> print(value)</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> x </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">where</span><span style="font-variant-ligatures: no-common-ligatures" class=""> x % </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">3</span><span style="font-variant-ligatures: no-common-ligatures" class=""> == </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span><span style="font-variant-ligatures: no-common-ligatures" class="">:</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3d1d81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"fizz", terminator: ""</span><span style="font-variant-ligatures: no-common-ligatures" class="">)</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class="">continue</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> x </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">where</span><span style="font-variant-ligatures: no-common-ligatures" class=""> x % </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">5</span><span style="font-variant-ligatures: no-common-ligatures" class=""> == </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span><span style="font-variant-ligatures: no-common-ligatures" class="">:</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3d1d81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"buzz", terminator: ""</span><span style="font-variant-ligatures: no-common-ligatures" class="">)</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures;" class="">continue</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">default</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">:</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> print("")</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class="">break</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div></div><div class=""><br class=""></div><div class="">If you use the standard rules, it looks like this:</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">switch</span><span style="font-variant-ligatures: no-common-ligatures" class=""> value</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">{</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">case</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class="">_</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">:</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> print(value, terminator: </span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">""</span><span style="font-variant-ligatures: no-common-ligatures" class="">)</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> x </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">where</span><span style="font-variant-ligatures: no-common-ligatures" class=""> x % </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">3</span><span style="font-variant-ligatures: no-common-ligatures" class=""> == </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span><span style="font-variant-ligatures: no-common-ligatures" class="">:</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3d1d81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">" fizz"</span><span style="font-variant-ligatures: no-common-ligatures" class="">, terminator: </span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">""</span><span style="font-variant-ligatures: no-common-ligatures" class="">)</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class="">continue</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> x </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">where</span><span style="font-variant-ligatures: no-common-ligatures" class=""> x % </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">5</span><span style="font-variant-ligatures: no-common-ligatures" class=""> == </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span><span style="font-variant-ligatures: no-common-ligatures" class="">:</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3d1d81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">" buzz"</span><span style="font-variant-ligatures: no-common-ligatures" class="">, terminator: </span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">""</span><span style="font-variant-ligatures: no-common-ligatures" class="">)</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures;" class="">continue</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="color: rgb(187, 44, 162); font-variant-ligatures: no-common-ligatures;" class="">default</span><span style="font-variant-ligatures: no-common-ligatures;" class="">:</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3d1d81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">""</span><span style="font-variant-ligatures: no-common-ligatures" class="">)</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class="">break</span></div><div style="margin: 0px; font-size: 16px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div></div><div class=""><br class=""></div><div class="">-- E</div><div class=""><br class=""></div></body></html>