[swift-evolution] [Accepted with Revision] SE-0099 Restructuring Condition Clauses

Brandon Knope bknope at me.com
Fri Jun 10 14:48:11 CDT 2016

> On Jun 10, 2016, at 1:47 PM, Roth Michaels via swift-evolution <swift-evolution at swift.org> wrote:
> While I did not get a chance to review all the discussion in time to
> respond to the proposal, I am happy with the revised version that was
> approved (the semi-colons were a point of concern for me).  In addition
> to resolving ambiguity, this also resolved a pedigogical issue
> surrounding the 'where' keyword I encountered when teaching Swift.
> On Wed, Jun 08 2016 at 09:47:55 PM, Joe Groff via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 'where' keyword can be retired from its purpose as a boolean condition
>> introducer.
> When teaching Swift, I did discover that the requirement of 'where' in
> conditionals as expressed by this proposal was confusing and those I was
> teaching assumed they would use commas (or &&).

I completely understand this, but isn’t this because they just didn’t know the syntax existed?

After they learned about it, did they understand it? Did they like it? Hate it? That’s what I am very interested in hearing about

> I'll admit that at first the 'where' keyword surprised me as well, but I
> grew to like it and will be a little sad to see it replaced by comma
> instead of allowing 'where' or comma as I thought certain statements
> were easier to read with 'where’.

Exactly :/


> On Thu, Jun 09 2016 at 06:30:17 AM, Haravikk via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>    On 9 Jun 2016, at 09:47, Brent Royal-Gordon
>>    <brent at architechies.com> wrote:
>>        Can we get some clarification as to why ‘where’ is being chosen
>>        to be retired here? I’m deeply disappointed by that decision as
>>        enabling the consistent use of comma as a separator does not
>>        preclude the use of where for simple cases that don’t require
>>        it. I’m all for having a more usable separator for complex
>>        conditionals, but I rarely need it, meanwhile in common, simple
>>        conditional bindings and patterns I find the ‘where’ keyword a
>>        lot more readable, i.e:
>>        if let value = foo where foo > 5 { … }
>>    I think there may be a case for keeping the `where` keyword—but
>>    before, not after, the equals sign.
>>    if case .cartesian(let x, let y) where x != y = point { ... }
>>    if let value where value > 5 = foo { … }
>> That looks pretty strange visually though thanks to the assignment (it
>> kind of looks like x is being compared against y = point).
> I had this feeling as well.
>> While my reasons for liking where are mainly aesthetic once the need to
>> use it to get around separator issues goes away, it’s still a nice tool
>> for grouping statements visually, for example:
> This is the case for me as well, functionally I suppose I will not miss
> 'where', but for aesthetics I do think it made some statements cmore
> clear to read.
> --
> Roth
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