<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div></div><div>The advantage of not having to nest is that I can do all these nice monadic things with its. Just look at Scala's for-expression which does exactly that, mimicking Haskell's do-notation.</div><div>I would love support for that in Swift.</div><div><br></div><div>-Thorsten</div><div><br>Am 09.12.2015 um 23:11 schrieb Chris Eidhof via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>>:<br><br></div><blockquote type="cite"><div><meta http-equiv="Content-Type" content="text/html charset=utf-8">Exactly! Just like multiple-if-let is the same as flatMap on optionals, this is a better syntax for flatMap on arrays. <div class=""><br class=""></div><div class="">To make it more clear that it’s a nested loop, we could also consider:</div><div class=""><br class=""></div><div class="">for x in xs, for y in ys {</div><div class="">}</div><div class=""><br class=""></div><div class="">But I’m not sure if it actually is clearer. (You could totally still interpret this as a zip, rather than a flatMap).</div><div class=""><br class=""></div><div class="">Chris</div><div class=""><br class=""></div><div class=""><br class=""><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 09 Dec 2015, at 16:51, Maxwell Swadling <<a href="mailto:maxs@apple.com" class="">maxs@apple.com</a>> wrote:</div><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=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On 9 Dec 2015, at 1:44 PM, Douglas Gregor 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: 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=""><br class="Apple-interchange-newline">On Dec 9, 2015, at 1:43 PM, Brent Royal-Gordon <<a href="mailto:brent@architechies.com" class="">brent@architechies.com</a>> wrote:<br class=""><br class=""><blockquote type="cite" class=""><blockquote type="cite" class="">I think it could be really nice to extend the for-loop so that it can have multiple clauses. Much like in the if-let with multiple clauses, I could imagine a for-loop with multiple clauses:<br class=""><br class="">var cards: [(Suit,Rank)] = []<br class="">for x in suits, y in ranks {<br class="">cards.append((x,y))<br class="">}<br class=""></blockquote><br class=""><br class="">Isn’t this just<br class=""><br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>for (x, y) in zip2(suits, ranks) {<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>}<br class=""><br class="">?<br class=""></blockquote><br class="">No, apparently it’s supposed to be all permutations of both types. But I too read it as syntactic sugar for a zip, which I think is a great reason not to add this syntax.<br class=""></blockquote><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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: 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="">Ah. In that case, I’d much rather have a library function that indicates that we’re getting all permutations. This doesn’t feel like it belongs in the language at all, but in the library.</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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 class="Apple-tab-span" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: pre; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"> </span><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">- Doug</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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; 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font-size: 12px; font-style: normal; font-variant: 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=""><a href="mailto:swift-evolution@swift.org" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">swift-evolution@swift.org</a><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">https://lists.swift.org/mailman/listinfo/swift-evolution</a></div></blockquote></div><div class=""><br class=""></div>We do have this library function, it is flatMap.<div class=""><br class=""></div><div class="">The desired feature here seems to be desugaring for loops <br class=""><div class=""><br class=""></div><div class="">for x in xs, y in ys, z in zs {</div><div class=""> ...</div><div class="">}</div><div class=""><br class=""></div><div class="">into:</div><div class=""><br class=""></div><div class="">xs.flatMap { x in ys.flatMap { y in zs.map { z in ... } } }</div><div class=""><br class=""></div><div class="">So as above you would get:</div><div class=""><br class=""></div><div class="">suits.flatMap { x in ranks.map { y in cards.append((x,y)) } }</div><div class=""><br class=""></div><div class=""><br class=""></div></div></div></div></blockquote></div><br class=""></div></div>
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