<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="">Le 27 mai 2017 à 19:43, Dave Abrahams via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> a écrit :</div><br class="Apple-interchange-newline"><div class=""><br 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;" 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="">on Thu May 25 2017, Gwendal Roué <</span><a href="mailto:swift-evolution@swift.org" 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="">swift-evolution@swift.org</a><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="">> wrote:</span><br 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;" class=""><br 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;" 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=""><blockquote type="cite" class="">Furthermore, this probably comes up most commonly with dictionaries,<br class="">since they're a sequence of tuples. The element tuple for<br class="">dictionaries has element labels (key: Key, value: Value), so instead<br class="">of writing `{ tuple in let (key, value) = tuple; f(key, value) }`,<br class="">you could use the implicit argument and write `{ f($0.key, $0.value)<br class="">}`.<br class=""><br class="">-Joe<br class=""></blockquote><br class="">I've migrated a project from Swift 3 to Swift 4 (relevant commit:<br class=""><a href="https://github.com/groue/GRDB.swift/commit/4f26cbcacf7b783c9c503f2909f2eb03ef7930fe" class="">https://github.com/groue/GRDB.swift/commit/4f26cbcacf7b783c9c503f2909f2eb03ef7930fe</a>)<br class=""><br class="">Joe is right, dictionaries, as handy as they are, are particularly affected. But $0 is hardly a<br class="">panacea.<br class=""><br class="">What I regret the most with the change is the lost ability to give<br class="">*relevant names* to tuple elements (and sometimes with the forced<br class="">introduction of a phony variable that has no relevant name (like<br class="">"pair").<br class=""></blockquote><br 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;" 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="">Not saying there's no problem here, but `kv` (or `keyValue` if you must)</span><br 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;" 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="">works pretty well for this. At least it isn't purely a reflection of</span><br 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;" 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="">the type and gives some hint as to semantics.</span></div></blockquote><br class=""></div><div>Let me please try to be understood:</div><div><br class=""></div><div>A dictionary is a convenience type, with many many purposes. One rarely thinks of a dictionary as a "dictionary". It's more often a "cache", or a "name1 to name2 mapping", as in "name to position mapping", "lowercase string to case-preserved string mapping", or whatever you want.</div><div><br class=""></div><div>The "kv", "pair", "key", "value" identifiers are not only irrelevant, they actively hinder code readability. Compare:</div><div><br class=""></div><div>- ...map { $0.key ... $0.value ... }</div><div>- ...map { (name, position) in name ... position ... }</div><div><br class=""></div><div>Gwendal</div><div><br class=""></div></body></html>