[swift-evolution] [Pitch] Retiring `where` from for-in loops

Goffredo Marocchi panajev at gmail.com
Fri Jun 10 14:06:49 CDT 2016

I was not advocating the lack of constraints, programmers like all other
artists (and engineers, which are artists too ;)), but that the beauty is
the moderation of the two extremes :). ... and that architects leave the
problems you are talking about to the structural engineer :P.

Gravity is a constrain, but a different one than having to use only a
certain pencil to do your sketches with and only being able to use Windows
95 OSR 3 to work on or even weirder limitations.

On Fri, Jun 10, 2016 at 7:59 PM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:

> On Fri, Jun 10, 2016 at 1:11 PM, Goffredo Marocchi <panajev at gmail.com>
> wrote:
>> I think sometimes the community in this mailing list loses sight on the
>> fact that coding is a creative  endeavour much similar to architectural
>> design or painting. There may be math and well researched and structured
>> ideas in place, but it requires creativity too.
> Architects are constrained to craft buildings that will stand in the face
> of gravity, and even painters don't have pigments for every color visible
> to the human eye. There's a wonderful novel, _Gadsby_, written without the
> letter 'e'; I haven't read it but I understand it's truly an
> accomplishment. This is not so drastic here. In this case, the apt analogy
> would be that we find the letter 'a with circle on top' to be posing some
> pesky problems; do you think you could write a novel in English without
> using 'a with circle on top'? I wager that your creativity will not suffer
> (unless your novel describes a trip to IKEA, in which case I'm sorry).
>> Trying to force a strict one size fits all The One True standard usually
>> ends up fragmenting the standard further, by adding yet another take on
>> what is the most orthodox implementation and who are the heretics...
>> I do not think dismissing the idea of having more than one way of
>> skinning the proverbial cat as an anti-goal is doing a good service to the
>> community or the language as it completely disregards context, people
>> differing idea of the subjective best coding style and patterns (which
>> pattern do I use? Which algorithm do I use to sort this data set with? A
>> good engineer will give you a direct and concise answer, but a better one
>> will say "it depends... What's the context? What is the problem I need to
>> solve, what are the constraints and the data set I am working on?").
>> The way some users seem to want Swift to follow sounds like protecting
>> users from mistakes by sometimes removing the ability which could lead to
>> mistakes in the first place, but that removes all the good things you could
>> do if you were to trust developers with the extra responsibility.
>> Sent from my iPhone
>> On 10 Jun 2016, at 18:30, let var go via swift-evolution <
>> swift-evolution at swift.org> wrote:
>> I respect that anti-goal, but I think being over-rigid about limiting
>> developers' choice of expression is also an anti-goal.
>> To me, it is like guard statements vs. if-let statements. Some people
>> find one to be more clear than the other. Often times the best choice
>> depends on the context. Sometimes a guard statement can be re-written as an
>> if-let statement in a way that makes the code more clear, and vice versa.
>> And different people will inevitably have different personal preferences -
>> their own "style", if you will - and will favor one over the other. But it
>> would be a mistake to force everyone into one box in order to prevent the
>> fracturing of the Swift community into "dialects."
>> But most importantly (and this is really the kicker for me) there are
>> times when the "where" syntax provides the maximum amount of clarity in the
>> context of my code, and I don't want to lose that expressive power.
>> On Fri, Jun 10, 2016 at 10:17 AM Xiaodi Wu <xiaodi.wu at gmail.com> 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 <letvargo at 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 at swift.org> wrote:
>>>>> On Fri, Jun 10, 2016 at 11:23 AM, Sean Heber via swift-evolution <
>>>>> swift-evolution at 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
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