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

[Christopher Kornher]

> On May 31, 2016, at 1:59 PM, Brandon Knope <bknope at me.com> wrote:
> 
> Except "b" is the main focus of the where clause and b was just in the preceding if condition. 
> 
> I feel like we are trying to find ways to break the current where clause even though we've enjoyed it for almost a year now. I had no idea it was problematic and restrictive. I thought it made its intent very clear...leading to very readable code. 
> 
> Pretty soon almost every construct but conditionals will be allowed to have where clauses, and THAT seems inconsistent to me. 
> 
> ...what exactly is the current problem? Can someone show me a real world example?? I've already forgotten it in all of this discussion -_-
> 
> Brandon 
> 

I did this to explore why many people are reluctant to give-up ‘where’. The use of ‘where' seems intuitive to mess well, and I did not understand why. It seems to natural group all logic concerning a constant with its definition and this seems to be a way to do that.

These rules add restrictions, but it does group related elements.  I am not convinced that this improves the language, but I though that it was worth exploring.  


> On May 31, 2016, at 3:47 PM, Xiaodi Wu via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> 
>> 
>> 
>> On Tue, May 31, 2016 at 2:45 PM, Christopher Kornher via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>> 
>>> Not allowed:
>>> …
>>> let a = a
>>> let b = b where b > 10 && a > 5
>>> 
>>> Why would this not be allowed by your rule? You're making use of `b` in your where clause. As I demonstrated above, essentially any assertion can be rewritten to work around your rule. In general:
>> 
>> It is not allowed because  ‘a’ is defined in the line above. It must be defined in the ‘if let’ associated with the where in which it is mentioned.
>> 
>> That's a much more restrictive where clause than you proposed earlier. You'd not be able to write:
>> 
>> ```
>> let b = b where b > anyOtherVariable
>> ``` 
>> 
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