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

Thorsten Seitz tseitz42 at icloud.com
Tue May 31 10:02:57 CDT 2016


Like some others on this list I prefer the `where` because it stands out and therefore increases readability by visually separating semantically different clauses.

-Thorsten 

> Am 31.05.2016 um 07:10 schrieb Xiaodi Wu <xiaodi.wu at gmail.com>:
> 
> Of course, an alternative is to eliminate `where` for all uses of `case` as well.
>> On Mon, May 30, 2016 at 11:55 PM Thorsten Seitz via swift-evolution <swift-evolution at swift.org> wrote:
>> 
>> > Am 29.05.2016 um 17:11 schrieb Thorsten Seitz via swift-evolution <swift-evolution at swift.org>:
>> >
>> >
>> >> Am 28.05.2016 um 22:35 schrieb Chris Lattner <clattner at apple.com>:
>> >>
>> >>
>> >>> On May 28, 2016, at 12:07 PM, Thorsten Seitz <tseitz42 at icloud.com> wrote:
>> >>>
>> >>> What about requiring `let` before each binding and `case` before each pattern?
>> >>>
>> >>> guard case let x = a, case let y = b, let z = c, x == y else { … }
>> >>>
>> >>> Now `let z = c` can only be a let-binding and not a pattern matching clause.
>> >>
>> >> Yes, that would be enough to solve the ambiguity.  The problem with that is that it eliminates a commonality with var/let declarations, which can declare multiple variables.
>> >
>> > var/let declarations are sufficiently different from let-bindings IMO that this commonality could be dropped.
>> 
>> In addition the proposal would result in eliminating a commonality of `case` clauses allowing a `where` clause everywhere except in conditional clauses which is worse.
>> I'd much rather prefer to drop the commonality with var/let declarations!
>> 
>> -Thorsten
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