[swift-evolution] [Pitch] Introducing `Unwrappable` protocol

[David Hart]

> On 8 Mar 2017, at 03:27, Greg Parker via swift-evolution <swift-evolution at swift.org> wrote:
> 
> 
>> On Mar 7, 2017, at 3:49 PM, Jaden Geller via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
>> It’s worth mentioning that the normal let binding can be used for pattern matching:
>>   let (a, b, c) = foo()
>> 
>> This nicely parallels the existing case syntax:
>>   if case let .blah(a, b, c) = bar() { … }
>> It would feel inconsistent if the order switched when in a conditional binding.
>> 
>> I would prefer that `case` was removed to best mirror the normal syntax, requiring `?` or `.some` to be used for optionals
>>   if let .blah(a, b, c) = bar() { … }
>>   if let unwrapped? = wrapped { … }
>>   if let .some(unwrapped) = wrapped { … }
>> but I realize this is source-breaking, so I’m happy with the existing syntax.
> 
> We tried `if let unwrapped? = wrapped` some time ago. It was unbelievably unpopular. We changed it back.

Who was it unpopular with? We’re talking about people inside Apple before Swift was released, right?

> -- 
> Greg Parker     gparker at apple.com <mailto:gparker at apple.com>     Runtime Wrangler
> 
> 
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