On Mon, Jun 13, 2016 at 11:50 AM, let var go <letva...@gmail.com> wrote:
> No, the key difference between for...in and forEach is that for...in > allows for early exit. They both allow you to 'continue', though in forEach > it is called 'return': > > // This prints odd numbers, skipping ("continuing") past the even numbers: > (0..<100).forEach { if $0 % 2 == 0 { return } else { print($0) } } > > Early-exit ('break') is a different beast and requires a for...in loop. > > You missed my main point. In some situations even 'continue' may prove to > be useful. It is not my preferred method. > > Why do you say, "Swift is not a live-and-let-live language?" Where do you > get that from? Are you really saying that there is not room in the Swift > community for people with different coding styles and preferences? I truly > believe that that attitude will be very harmful to the long term future of > the language. > In the words of Chris Lattner: We intentionally want Swift to have a common “center of gravity” and be an “opinionated” language, rather than fall to the “design by committee” approach that leads to a watered-down design. > > On Mon, Jun 13, 2016 at 9:29 AM Xiaodi Wu <xiaodi...@gmail.com> wrote: > >> See, the key difference between for...in and .forEach() is that one >> allows for continue and break and the other doesn't. Swift is not a >> live-and-let-live language: if you truly believe that using continue leads >> to bad code, then propose its removal or the removal of for...in altogether. >> >> On Mon, Jun 13, 2016 at 11:21 let var go <letva...@gmail.com> wrote: >> >>> No, I wouldn't eliminate 'continue'. Even though I consider it a >>> sub-optimal solution, I would keep it in the language. Why? A couple of >>> reasons: >>> >>> 1) I don't like it, but even 'continue' may be the best available >>> solution in the context of a particular problem. I will look for other >>> options first, but I don't rule out the possibility that there might come a >>> time when it is the right tool for the job. >>> >>> 2) Some people like it. Not everyone feels the same way about it as me. >>> Some of the people who like it are better programmers than me. I have a lot >>> to learn, and someday I might discover that I love 'continue' after all. >>> Until then, live-and-let-live is what I say. Everyone should control their >>> own flow :) Keep your hands off my 'where' and I'll keep my hands off your >>> 'continue' :) >>> >>> On Mon, Jun 13, 2016 at 8:56 AM Xiaodi Wu <xiaodi...@gmail.com> wrote: >>> >>>> On Mon, Jun 13, 2016 at 10:44 AM, let var go <letva...@gmail.com> >>>> wrote: >>>> >>>>> I think we must be reading different discussions. >>>>> >>>>> What I have seen in this discussion is the following: >>>>> >>>>> a) The need to filter a for-in loop doesn't arise that often; but, >>>>> b) When it does arise, everyone who has chimed in on this thread >>>>> (except the two people who are proposing the change) thinks that the >>>>> "where" clause is the clearest, most expressive way to do it. >>>>> >>>>> Something that would help me get on board with this change is more >>>>> evidence about what kind of problems it is actually creating. >>>>> >>>>> As best I can tell, this proposal got started because "somewhere" some >>>>> new programmers (no one knows how many) expressed some confusion (no one >>>>> knows how seriously they were confused, or how long it took them to figure >>>>> it out) about how the where clause worked in a for-in loop. For all we >>>>> know, once they learned the way it works, they may have said, "Hey that's >>>>> cool! I'm gonna use that from now on!" >>>>> >>>>> In other words, you seem to be talking about removing a feature that >>>>> is liked by *a lot* people, based on some unsubstantiated reports of user >>>>> error that may or may not have been totally unsubstantial. >>>>> >>>>> I don't want new programmers to be confused, either, but the "where" >>>>> clause is such a basic programming construct - the keyword is new, but the >>>>> idea itself is as old as programming - that I don't mind expecting new >>>>> programmers to learn how to use it. The learning curve should be >>>>> incredibly >>>>> short - it is nothing more than a filter operation. >>>>> >>>>> There's something else here that is really important to me, though I >>>>> don't know how others feel about it. >>>>> >>>>> Using the guard...continue approach that you are promoting is a code >>>>> smell. It puts control-flow logic inside the for-in loop. That is >>>>> something >>>>> I have always tried to avoid. I know that the language allows for it, but >>>>> I >>>>> believe it is bad programming practice. In fact, if you get rid of the >>>>> `where` keyword, I'm still not going to use guard...continue. I'll just >>>>> filter the collection first and then loop it. >>>>> >>>> >>>> This is quite the statement. It sounds like you'd be for the >>>> elimination of `continue`? >>>> >>>> >>>>> >>>>> It is a code smell for the same reason that messing with the index >>>>> inside a for;; loop was a code smell. I was always taught never to do >>>>> this: >>>>> >>>>> for var i = 0; i < array.count, i++ { >>>>> if iWantThisToLoopAnExtraTime { >>>>> i-- >>>>> } >>>>> } >>>>> >>>>> Why? Because code like that is confusing. It becomes difficult to know >>>>> how many times the loop will execute, what the looping logic is, etc. >>>>> Sure, >>>>> I might get away with it most of the time, but it is bad practice and >>>>> there >>>>> is always a better way to do what you want to do. The only thing that >>>>> keeps >>>>> you from the better way is laziness. >>>>> >>>>> The same is true (albeit to a lesser degree) for the guard...continue. >>>>> It may not be as extreme, but it is still a code smell. It divides the >>>>> control-flow logic into two parts - one outside the loop, and one inside >>>>> the loop, and it suddenly becomes twice as easy to miss something. >>>>> >>>>> Using for-in-where, all of the control-flow logic is on one single >>>>> line, and once it is known that "where" operates as a filter operation, it >>>>> all works together in a single, harmonious statement that declares exactly >>>>> what is going to happen in a way that is totally unambiguous. >>>>> >>>>> So by getting rid of the "where" clause, I believe that you are >>>>> actually encouraging bad programming practice. Instead of encouraging the >>>>> new user to learn this very simple construct that will ultimately make >>>>> their code safer and more expressive without dividing their control-flow >>>>> logic unnecessarily into two separate parts, you are encouraging them to >>>>> just "do what they know". I think that is terrible, and you are doing them >>>>> a disservice. >>>>> >>>>> And from a personal standpoint, you are telling me that I have to >>>>> write smelly code, even though there is this perfectly good non-smelly >>>>> option sitting right there, because you don't want someone else to have to >>>>> learn something. >>>>> >>>>> On Mon, Jun 13, 2016 at 5:29 AM Xiaodi Wu <xiaodi...@gmail.com> wrote: >>>>> >>>>>> I think this discussion has made it pretty plain that what is claimed >>>>>> to be 'so useful' is barely ever used. Moreover, it provides no >>>>>> independent >>>>>> uses. The point of these pitches is to sound out arguments, not, as far >>>>>> as >>>>>> I was aware, to take a vote. >>>>>> >>>>>> On Mon, Jun 13, 2016 at 1:54 AM Jose Cheyo Jimenez < >>>>>> ch...@masters3d.com> wrote: >>>>>> >>>>>>> --1 >>>>>>> >>>>>>> I think it would be a waste of the community's time to do a formal >>>>>>> review when only two people are in favor of this removal. >>>>>>> >>>>>>> 'for in where' is so useful especially since we don't have for;;; >>>>>>> loops anymore. I'd say leave this alone; the majority doesn't want this >>>>>>> changed. >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Jun 10, 2016, at 10:17 AM, Xiaodi Wu via swift-evolution < >>>>>>> swift-evolution@swift.org> wrote: >>>>>>> >>>>>>> I think this idea--if you don't like it, then you don't have to use >>>>>>> it--is indicative of a key worry here: it's inessential to the language >>>>>>> and >>>>>>> promotes dialects wherein certain people use it and others wherein they >>>>>>> don't. This is an anti-goal. >>>>>>> >>>>>>> On Fri, Jun 10, 2016 at 12:10 let var go <letva...@gmail.com> wrote: >>>>>>> >>>>>>> Leave it in! >>>>>>>> >>>>>>>> It's a great little tool. I don't use it very often, but when I do >>>>>>>> it is because I've decided that in the context of that piece of code it >>>>>>>> does exactly what I want it to do with the maximum amount of clarity. >>>>>>>> >>>>>>>> If you don't like it, then don't use it, but I can't see how it >>>>>>>> detracts from the language at all. >>>>>>>> >>>>>>>> The *only* argument that I have heard for removing it is that some >>>>>>>> people don't immediately intuit how to use it. I didn't have any >>>>>>>> trouble >>>>>>>> with it at all. It follows one of the most basic programming patterns >>>>>>>> ever: >>>>>>>> "For all x in X, if predicate P is true, do something." The use of the >>>>>>>> keyword "where" makes perfect sense in that context, and when I read >>>>>>>> it out >>>>>>>> loud, it sounds natural: "For all x in X where P, do something." That >>>>>>>> is an >>>>>>>> elegant, succinct, and clear way of stating exactly what I want my >>>>>>>> program >>>>>>>> to do. >>>>>>>> >>>>>>>> I don't doubt that it has caused some confusion for some people, >>>>>>>> but I'm not sold that that is a good enough reason to get rid of it. It >>>>>>>> seems strange to get rid of a tool because not everyone understands >>>>>>>> how to >>>>>>>> use it immediately, without ever having to ask a single question. As >>>>>>>> long >>>>>>>> as its not a dangerous tool (and it isn't), then keep it in the >>>>>>>> workshop >>>>>>>> for those times when it comes in handy. And even if there is some >>>>>>>> initial >>>>>>>> confusion, it doesn't sound like it lasted that long. It's more like, >>>>>>>> "Does >>>>>>>> this work like X, or does this work like Y? Let's see...oh, it works >>>>>>>> like >>>>>>>> X. Ok." That's the entire learning curve...about 5 seconds of curiosity >>>>>>>> followed by the blissful feeling of resolution. >>>>>>>> >>>>>>>> On Fri, Jun 10, 2016 at 9:32 AM Xiaodi Wu via swift-evolution < >>>>>>>> swift-evolution@swift.org> wrote: >>>>>>>> >>>>>>> On Fri, Jun 10, 2016 at 11:23 AM, Sean Heber via swift-evolution < >>>>>>>>> swift-evolution@swift.org> wrote: >>>>>>>>> >>>>>>>> > And to follow-up to myself once again, I went to my "Cool 3rd >>>>>>>>>> Party Swift Repos" folder and did the same search. Among the 15 >>>>>>>>>> repos in >>>>>>>>>> that folder, a joint search returned about 650 hits on for-in (again >>>>>>>>>> with >>>>>>>>>> some false positives) and not a single for-in-while use. >>>>>>>>>> >>>>>>>>>> Weird. My own Swift projects (not on Github :P) use “where” all >>>>>>>>>> the time with for loops. I really like it and think it reads *and* >>>>>>>>>> writes >>>>>>>>>> far better as well as makes for nicer one-liners. In one project, by >>>>>>>>>> rough >>>>>>>>>> count, I have about 20 that use “where” vs. 40 in that same project >>>>>>>>>> not >>>>>>>>>> using “where”. >>>>>>>>>> >>>>>>>>>> In another smaller test project, there are only 10 for loops, but >>>>>>>>>> even so one still managed to use where. >>>>>>>>>> >>>>>>>>>> Not a lot of data without looking at even more projects, I admit, >>>>>>>>>> but this seems to suggest that the usage of “where” is going to be >>>>>>>>>> very >>>>>>>>>> developer-dependent. Perhaps there’s some factor of prior background >>>>>>>>>> at >>>>>>>>>> work here? (I’ve done a lot of SQL in another life, for example.) >>>>>>>>>> >>>>>>>>> That is worrying if true, because it suggests that it's enabling >>>>>>>>> 'dialects' of Swift, an explicit anti-goal of the language. >>>>>>>>> >>>>>>>> >>>>>>>>>> I feel like “where” is a more declarative construct and that we >>>>>>>>>> should be encouraging that way of thinking in general. When using >>>>>>>>>> it, it >>>>>>>>>> feels like “magic” for some reason - even though there’s nothing >>>>>>>>>> special >>>>>>>>>> about it. It feels like I’ve made the language work *for me* a >>>>>>>>>> little bit >>>>>>>>>> rather than me having to contort my solution to the will of the >>>>>>>>>> language. >>>>>>>>>> This may be highly subjective. >>>>>>>>>> >>>>>>>>>> l8r >>>>>>>>>> Sean >>>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>>> swift-evolution mailing list >>>>>>>>>> swift-evolution@swift.org >>>>>>>>>> https://lists.swift.org/mailman/listinfo/swift-evolution >>>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>> swift-evolution mailing list >>>>>>>>> swift-evolution@swift.org >>>>>>>>> https://lists.swift.org/mailman/listinfo/swift-evolution >>>>>>>>> >>>>>>>> _______________________________________________ >>>>>>> swift-evolution mailing list >>>>>>> swift-evolution@swift.org >>>>>>> https://lists.swift.org/mailman/listinfo/swift-evolution >>>>>>> >>>>>>>
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