<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="">On Dec 22, 2016, at 8:43 PM, Robert Widmann via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><div><blockquote type="cite" class=""><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Do you think there’s room for a more general <a href="https://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms" class="">Pattern Synonyms-like</a> feature that could extend this to things that look tuple-y? We had a short conversation on Twitter 'round about the release of Swift 1.2 about Swiftz’s <a href="https://github.com/typelift/Swiftz/blob/master/Sources/HList.swift#L185" class="">HList</a> implementation and my desire to be able to destructure them into tuples for native pattern matching.</div><div class=""><br class=""></div><div class="">~Robert Widmann</div><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Dec 22, 2016, at 9:46 AM, Joe Groff 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=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; 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-size-adjust: auto; -webkit-text-stroke-width: 0px;" class=""><br class="Apple-interchange-newline">On Dec 17, 2016, at 9:43 PM, Mathew Sanders via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class="">I've just joined the list (hi!) so not sure if this has been discussed in the past.<br class=""><br class="">Curious to hear if a future version of Swift might ever include some sort of pattern-matching extended to Arrays. Maybe something like the following:<br class=""><br class="">let numbers: [Int]<br class=""><br class="">switch numbers {<br class="">case []:<br class=""> // to match an empty array<br class=""><br class="">case [1, 2, 3]:<br class=""> // to match array with specific values<br class=""><br class="">case [_, _, _]:<br class=""> // to match array with 3 Ints<br class=""><br class="">case let [first, last]:<br class=""> // match a 2 element array and bind first and last elements<br class=""><br class="">case let [first, next...]:<br class=""> // to match array with at least one element<br class=""> // bind first element, and bind other elements (could be empty)<br class=""> // first: Int, next: [Int] <br class="">}<br class=""><br class="">I love the pattern matching on tuples, and would love to see if extend to Arrays as well, but not sure if it fits with future goals for the language.<br class=""></blockquote><br style="font-family: Helvetica; font-size: 12px; 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;" class=""><span style="font-family: Helvetica; font-size: 12px; 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="">Yeah, this is something I've wanted to add for a while, along with pattern matching for dictionaries, which together with array matching I think would make a lot of JSON/plist wrangling much more pleasant. Since it's an additive feature, it's taken a backseat to more pressing source- and ABI-breaking changes we've wanted to get out of the way first.</span><br style="font-family: Helvetica; font-size: 12px; 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;" class=""></div></blockquote></div></div></div></blockquote></div><br class=""><div class="">I'd be excited to see a feature like this for arrays, dictionaries, and array-like items such as strings. I know that this cannot be addressed for a while, but I'd love to see the idea formalized a bit and placed on a list somewhere so it doesn't just disappear into the aether. </div><div class=""><br class=""></div><div class="">It's a pity we don't have a formal registry for "Some Day" items like this that get mentioned on-list, but don't properly fit into Jira or the SE pull-request queue.</div><div class=""><br class=""></div><div class="">-- E</div><div class=""><br class=""></div></body></html>