<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 class="">I’m not a big fan of the C-style for loop, mostly because i find the parts of it badly separated by those tiny semicolons which are easily overlooked.</div><div class=""><br class=""></div><div class="">Therefore for me it would be ok if the C-style for loop would be dropped but transforming its syntax into more Swift like syntax like suggested by Tyler might be even better as Roland and Tyler made some good points about advantages of the for loop (especially the guaranteed execution of the increment part). Being able to have the loop variable scoped locally to the loop is another advantage over the while loop.</div><div class=""><br class=""></div><div class="">Moving the incrementation part after the loop body as suggested by Tyler puts too much distance between the parts defining the loop mechanics IMHO (although I have to admit that it makes the order very clear), so I’d rather stay more closely with the original syntax, just eliminating the semicolons.</div><div class=""><br class=""></div><div class="">Therefore I’d like to suggest the following syntax (for-while-loop):</div><div class=""><br class=""></div>for var x = start while x <= end loop x += delta {<div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>// more than a few lines of code with early escape continues<br class=""><div class="">}</div><div class=""><br class=""></div><div class="">The initialization part (between „for" and „while“) and the loop part (after „loop“) are allowed to contain more than one statement.</div><div class="">The scope of all variables introduced (in the example „x“) is local to the loop.</div><div class=""><br class=""></div><div class="">Additionally the following form (for-until-loop) could be provided:</div><div class=""><br class=""></div><div class="">for var x = start until x > end loop x += delta {<div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>// more than a few lines of code with early escape continues<br class=""><div class="">}</div></div></div><div class=""><br class=""></div><div class="">Question: should the initialization part be restricted to var declarations or should it allow all statements?</div><div class=""><br class=""></div><div class="">Alternatives to the „loop“ keyword might be: iterate (a bit long), step, advance, next</div><div class=""><br class=""></div><div class="">Thorsten</div><div class=""><br class=""></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">Am 05.12.2015 um 11:27 schrieb Tyler Cloutier <<a href="mailto:cloutiertyler@aol.com" class="">cloutiertyler@aol.com</a>>:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="content-type" content="text/html; charset=utf-8" class=""><div dir="auto" class=""><div class="">Hmm, yeah, that is definitely a good point. It can be easy enough to throw a continue into a while loop an completely skip the increment step. Of course you could add syntax to a while loop to allow for block/loop scoping of variables and then it might be tempting to add some finally logic to ensure that the incrementing is never skipped. Which, then what you have is a C style for loop with unfamiliar/unprecedented syntax, which would be silly.</div><div class=""><br class=""></div><div class="">Perhaps the question is, is it worth keeping the C style around for loop syntax for these particular types of uses?</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">On a total side note, I figure while I'm proposing silly things and decidedly terrible syntax, I might as well mention that when I originally began programming I was confused about the need for two different styles of loops. It seemed like "while" was a special case of "for" and was redundant (but made for a nicer looking syntax). An interesting thought experiment is to think about what dropping "while" might look like.</div><div class=""><br class=""></div><div class="">Just like there is for-in</div><div class=""><br class=""></div><div class="">for x in someGenerator {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>// code</div><div class="">}</div><div class=""><br class=""></div><div class="">There could also be for-if-repeat and for-repeat-if</div><div class=""><br class=""></div><div class="">for var x = 0 if x < 7 repeat {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>// code</div><div class="">} then x + 7</div><div class=""><br class=""></div><div class="">for var x = 0 repeat {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>// code</div><div class="">} if x < 7 then x + 7</div><div class=""><br class=""></div><div class="">Certainly an unnecessary change considering the problem at hand and has obvious downsides, but I think fun to think about.</div><div class=""><br class=""></div><div class="">Tyler<br class=""><div class=""><div class=""><br class=""></div></div></div><div class=""><br class="">On Dec 4, 2015, at 11:54 PM, Roland King <<a href="mailto:rols@rols.org" class="">rols@rols.org</a>> wrote:<br class=""><br class=""></div><blockquote type="cite" class=""><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class="">I must be the only person who still likes C-style for loops on occasion. eg a loop with something floating point <div class=""><br class=""></div><div class="">for var floatingThing = start ; floatingThing <= end ; floatingThing += delta</div><div class="">{</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>// more than a few lines of code with early escape continues</div><div class="">}</div><div class=""><br class=""></div><div class="">shows intent of the loop very clearly, start, condition and increment all together at the top, and however you loop you always execute the increment part of the statement. Convert that to a while(), if you have a continue in the body, you have a good chance of not incrementing at all, or duplicating the increment code before every continue. So you can’t always nicely turn for into while. I second the point below about the loop variable being local to the for as well, I also like that. </div><div class=""><br class=""></div><div class="">In the float case yes you can use stride</div><div class=""><br class=""></div><div class="">for var floatingThing in start.stride( through : end, by : delta )</div><div class="">{</div><div class="">}</div><div class=""><br class=""></div><div class=""><div class="">but it’s not terribly pretty and you have to be sure whether you mean stride( through:, end:) or stride( to:, end:)</div><div class=""><br class=""></div><div class="">That’s not a problem with integers where you have the ‘0..<n’ syntax which reads very clearly in a for .. in construct but in other cases the old c-style for can be a clearer read than for .. in with an iterator. </div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On 5 Dec 2015, at 15:14, Tyler Cloutier <<a href="mailto:cloutiertyler@aol.com" class="">cloutiertyler@aol.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="content-type" content="text/html; charset=utf-8" class=""><div dir="auto" class=""><div class="">Indeed. Python doesn't have it, and there isn't much concern about the learning curve or the missing functionality there, it seems. I actually didn't even realize it was missing from Python until I stopped and thought about it.</div><div class=""><br class=""></div><div class="">At first I was concerned about losing C style for loops, but I really can imagine a scenario in which they are more succinct while still maintaining clarity of intent. Plus they're a pain to type out.</div><div class=""><br class=""></div><div class="">From time to time when programming in C or JS I will include more than one statement or more complicated logic in the increment part of the for loop (perhaps move 2 indices in a complicated way), but perhaps that would be clearer just to implement as a while loop with the logic at the end. </div><div class=""><br class=""></div><div class="">One thing I will say is that it's nice to have your loop variables scoped to the loop, which is more difficult (impossible?) to accomplish with a while loop.</div><div class=""><br class=""></div><div class="">Perhaps some while loop syntax like:</div><div class=""><br class=""></div><div class="">while (x < someThing) start var x = 0, y = 11 {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>x += someOtherThing</div><div class="">}</div><div class=""><br class=""></div><div class="">Which is decidedly terrible syntax, but that's kind of the idea anyway.</div><div class=""><br class=""></div><div class="">Tyler</div><div class=""><br class=""></div><div class=""><br class=""><br class=""><div class=""><div class=""><br class=""></div></div></div><div class=""><br class="">On Dec 4, 2015, at 3:21 PM, Colin Cornaby <<a href="mailto:colin.cornaby@mac.com" class="">colin.cornaby@mac.com</a>> wrote:<br class=""><br class=""></div><blockquote type="cite" class=""><div class=""><div class="">This is a nice solution that translates nicely without creating too much concern about changing the nature of an algorithm in a complex system. 👍<br class=""></div><div class=""><br data-mce-bogus="1" class=""></div><div class="">Should at least get a nice "fix it" in Xcode though. On survey, we do have developers using the C style syntax, but we're early in the process of transitioning.</div><div class=""><br class="">On Dec 04, 2015, at 02:52 PM, Johan Jensen <<a href="mailto:jj@johanjensen.dk" class="">jj@johanjensen.dk</a>> wrote:<br class=""><br class=""></div><div class=""><blockquote type="cite" class=""><div class="msg-quote"><div dir="ltr" class=""><div class=""><div class="">With the removal of post/pre-increment/decrement you might as well translate C-style for-loops to something akin to<br class=""><br class=""></div>for var i in 0..<10 {<br class=""> ...<br class="">}<br class=""><br class=""></div>If more advanced C-style for-loops are needed, I am sure most developers can use a while-loop (as mentioned by Ray Fix) until they get accustomed to Swift’s syntax. <br class=""></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Fri, Dec 4, 2015 at 11:37 PM, Joe Groff <span dir="ltr" class=""><<a href="mailto:jgroff@apple.com" data-mce-href="mailto:jgroff@apple.com" class="">jgroff@apple.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px #ccc solid; padding-left: 1ex;" data-mce-style="margin: 0 0 0 0.8ex; border-left: 1px #ccc solid; padding-left: 1ex;"><div style="word-wrap: break-word;" data-mce-style="word-wrap: break-word;" class=""><div class="">You might ease the pain by approximating C-style 'for' by a higher-order function:</div><div class=""><br class=""></div><div class="">func cStyleFor(@autoclosure init initializer: () -> (), @autoclosure test: () -> Bool, @autoclosure inc: () -> (), body: () throws -> ()) rethrows {</div><div class=""> // left as an exercise</div><div class="">}</div><div class=""><br class=""></div><div class="">var i = 0</div><div class="">cStyleFor(init: i = 0, test: i < 10, inc: ++i) {</div><div class=""> print(i)</div><div class="">}</div><div class=""><br class=""></div><div class="">-Joe</div><br class=""><div class=""><blockquote type="cite" class=""><span class=""><div class="">On Dec 4, 2015, at 2:33 PM, Colin Cornaby <<a href="mailto:colin.cornaby@mac.com" data-mce-href="mailto:colin.cornaby@mac.com" class="">colin.cornaby@mac.com</a>> wrote:</div><br class=""></span><div class=""><div class=""><span class=""><div class="">I was talking with people in the office about this proposal today, in since there has been such a long discussion already I'll just reply to the top of the tree just to get our take in before the review...</div><div class=""><br class=""></div><div class="">It's understood that Swift has better, more readable ways to do for loops, but C style for loops reduce friction for getting our C or C++ developers on board with Swift. Unless there is a gain elsewhere to be made in their removal, it would be nice to keep them. As we transition to Swift we can educate developers on better ways to iterate, but it would be nice to have one less thing in the way of getting people writing Swift code.</div><div class=""><br class=""></div><div class="">We work on a lot of algorithmic code which would be well suited for Swift. And again, I understand that C style for loops are redundant. But it's just one less speed bump in understanding for some of our developers or for porting pure C or C++ code without having to do as much re-validation of algorithms for accidental changes.</div><div class=""><br class=""></div><div class="">But if it's actively hurting some other part of the language we could probably be talked into it.</div><div class=""><br class="">On Dec 03, 2015, at 03:32 PM, Erica Sadun <<a href="mailto:erica@ericasadun.com" data-mce-href="mailto:erica@ericasadun.com" class="">erica@ericasadun.com</a>> wrote:<br class=""><br class=""></div></span><div class=""><blockquote type="cite" class=""><div style="word-wrap: break-word;" data-mce-style="word-wrap: break-word;" class=""><span class="">Does Swift still needs C-style for loops with conditions and incrementers? <div class=""><br class=""></div></span><div class=""><span class=""><div class=""><span class=""><Screen Shot 2015-12-03 at 4.30.15 PM.png></span></div><div class=""><br class=""></div></span><span class=""><div class="">More Swift-like construction is already available with <i class="">for-in</i>-statements and <i class="">stride</i>. </div><div class="">This would naturally starve the most common point for -- and ++ operators as well.</div></span></div><div class=""><br class=""></div><div class="">-- E</div><div class=""><br class=""></div><img src="https://u2002410.ct.sendgrid.net/wf/open?upn=OFgvmg1J6naJevMotmPmRgzA4p1gcL5s2O89Xj3c0DQwWaI2Zkn0T7Ir0ZhZX5JxhOGd3YPVKqo7V694c-2FCbs4q0bD0JoSqDmVKJlXSPFXuXDd-2BrSCkHJtpH2xW9FNCpsnXhG1CXNS-2BYiwa2avrMmz1klqK9v719yPdWuKsBJaZWK1jLmeFzO0xSa2YmruaZcuht7m9Jfq3dmNJI2I0f-2FXBDGxRbOsbfv3np8d7UbdU-3D" alt="" style="min-height: 1px; width: 1px; border-width: 0; padding: 0; margin: 0;" height="1" border="0" width="1" data-mce-src="https://u2002410.ct.sendgrid.net/wf/open?upn=OFgvmg1J6naJevMotmPmRgzA4p1gcL5s2O89Xj3c0DQwWaI2Zkn0T7Ir0ZhZX5JxhOGd3YPVKqo7V694c-2FCbs4q0bD0JoSqDmVKJlXSPFXuXDd-2BrSCkHJtpH2xW9FNCpsnXhG1CXNS-2BYiwa2avrMmz1klqK9v719yPdWuKsBJaZWK1jLmeFzO0xSa2YmruaZcuht7m9Jfq3dmNJI2I0f-2FXBDGxRbOsbfv3np8d7UbdU-3D" data-mce-style="min-height: 1px; width: 1px; border-width: 0; padding: 0; margin: 0;" class=""></div></blockquote></div><img src="https://u2002410.ct.sendgrid.net/wf/open?upn=RoDF4MveSEMYBIqIJA6ub1g8cOZ-2BVYvqV-2FqygPhjPn9dSCJq6hHxaKAHz2SgEMUEdmJq-2FsAifCMjI5P2wUJabdikvDGXS5zaIeiAW9VmUaiGFnyIyDQg2eHpiypFZpLqkwlMcSPttbgMOFlDhKsq7OZYMo2NC9kSDKFKCrEgV5UwEzHq3kVy3cvCkNDjAtbKUGaHHbyeqN4xiVXzGIrvZWzJxd5zQxuKao7pxdgeN1w-3D" alt="" style="min-height: 1px; width: 1px; border-width: 0; padding: 0; margin: 0;" height="1" border="0" width="1" data-mce-src="https://u2002410.ct.sendgrid.net/wf/open?upn=RoDF4MveSEMYBIqIJA6ub1g8cOZ-2BVYvqV-2FqygPhjPn9dSCJq6hHxaKAHz2SgEMUEdmJq-2FsAifCMjI5P2wUJabdikvDGXS5zaIeiAW9VmUaiGFnyIyDQg2eHpiypFZpLqkwlMcSPttbgMOFlDhKsq7OZYMo2NC9kSDKFKCrEgV5UwEzHq3kVy3cvCkNDjAtbKUGaHHbyeqN4xiVXzGIrvZWzJxd5zQxuKao7pxdgeN1w-3D" data-mce-style="min-height: 1px; width: 1px; border-width: 0; padding: 0; margin: 0;" class=""></div><span class=""> _______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" data-mce-href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" data-mce-href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class=""></span></div></blockquote></div><br class=""> <img src="https://u2002410.ct.sendgrid.net/wf/open?upn=KlmFWKNIEcyPEGx2Wqruu-2FaM6I0anrxIOlKS1pgqec64JmPD57SelWBf8STiBYuH5i3ko-2FtD2CU6chZgK79T9K3b3jBmmA5gMpTX5FF5mQnohQWqc0wkDTtpj-2FuZjbkeuGjx9YAUCDfU8j39LzH9ARiDcAzF3Bn8yEUzw1iLutsMLA-2FFkrnHXyH-2FxtuuASWC4iWLDeixQLwaQDsRNIRipB5PAbcL-2ByGZDjYiIwDQNRc-3D" alt="" style="min-height: 1px; width: 1px; border-width: 0; padding: 0; margin: 0;" height="1" border="0" width="1" data-mce-src="https://u2002410.ct.sendgrid.net/wf/open?upn=KlmFWKNIEcyPEGx2Wqruu-2FaM6I0anrxIOlKS1pgqec64JmPD57SelWBf8STiBYuH5i3ko-2FtD2CU6chZgK79T9K3b3jBmmA5gMpTX5FF5mQnohQWqc0wkDTtpj-2FuZjbkeuGjx9YAUCDfU8j39LzH9ARiDcAzF3Bn8yEUzw1iLutsMLA-2FFkrnHXyH-2FxtuuASWC4iWLDeixQLwaQDsRNIRipB5PAbcL-2ByGZDjYiIwDQNRc-3D" data-mce-style="min-height: 1px; width: 1px; border-width: 0; padding: 0; margin: 0;" class=""></div><br class="">_______________________________________________<br class=""> swift-evolution mailing list<br class=""> <a href="mailto:swift-evolution@swift.org" data-mce-href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class=""> <a href="https://lists.swift.org/mailman/listinfo/swift-evolution" rel="noreferrer" data-mce-href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class=""> <br class=""></blockquote></div><br class=""></div></div></blockquote></div>
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