[swift-evolution] [Review] SE-0099: Restructuring Condition Clauses

[Xiaodi Wu]

The chapter on optionals. Right in the thick of things about if let
binding, pattern matching, etc. It's a bit of a digression from the main
flow of things. In the PDF version it's p. 87 (at least, by Acrobat's
reckoning).

On Sun, May 29, 2016 at 15:28 Brandon Knope <bknope at me.com> wrote:

> What chapter is this in? I own this great book and would like to see what
> you are referring to!
>
> Thanks,
> Brandon
>
> On May 29, 2016, at 11:32 AM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:
>
> I totally agree with Brandon that it makes sense in the context. But I
> disagree with you: the behavior certainly isn't consistent. Those are two
> orthogonal evaluations.
>
> Personally, I've never been tripped up by the two different meanings of
> where clauses and I've used both. Yet, when it was presented to me in prose
> form in _Advanced Swift_ (a great read, btw), it was a shocking thing to
> realize.
>
> That these very experienced authors of the book felt compelled to point it
> out to their audience, who are ostensibly all experienced users of the
> language, suggests that there is something about the where clause not quite
> intuitive for all people. So I consider it a net positive to eliminate the
> inconsistency, whether or not it can be thought of as making sense.
>
> On Sun, May 29, 2016 at 11:15 Thorsten Seitz <tseitz42 at icloud.com> wrote:
>
>> Totally agree with Brandon. I don’t think that behavior is inconsistent.
>>
>> -Thorsten
>>
>>
>> Am 28.05.2016 um 22:18 schrieb Brandon Knope via swift-evolution <
>> swift-evolution at swift.org>:
>>
>> Doesn't this contextually make sense though?
>>
>> for, when read:
>> "for each value in collection where some condition is met" do this loop
>>
>> while, when read:
>> "while some condition where this constraint is met" do this loop
>>
>> It could just be because I know the behavior and am use to it, but I
>> think it makes sense contextually when used.
>>
>> Brandon
>>
>> On May 28, 2016, at 4:06 PM, Xiaodi Wu via swift-evolution <
>> swift-evolution at swift.org> wrote:
>>
>> I'm just gotta quote from Advanced Swift:
>>
>> Note that the where clause [in a for loop] does not work like the where
>> clause in a while loop. In a while loop, iteration stops once the value is
>> false, whereas in a for
>> loop, it functions like filter.
>>
>> On Sat, May 28, 2016 at 16:00 Haravikk <swift-evolution at haravikk.me>
>> wrote:
>>
>>>
>>> > On 28 May 2016, at 20:21, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:
>>> >
>>> > There's already an inconsistency in where clause behavior for `if` and
>>> `while` versus `for` loops. It's nice IMO that the former uses are
>>> eliminated in this proposal.
>>>
>>> Can you give an example? That sounds like something that should be
>>> addressed separately rather than just dropping it.
>>> Like I say I really like using it for basic bind + condition cases, so
>>> I’m very much opposed to just tossing where clauses.
>>
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