> Am 23.03.2016 um 13:11 schrieb Erica Sadun via swift-evolution
> <[email protected]>:
>
> I don't think this issue arises if you use the rule that functional closure
> arguments (returning values) shouldn't trail:
I'm not very fond of that rule, so I'd prefer the solution proposed by Chris :-)
-Thorsten
>
> func f(arr : [Int]?) {
> guard let x = arr?.map({ $0+1 }) else { // compiles
> preconditionFailure()
> }
> }
>
> That said, this seems like a positive tweak and I have no problem with its
> adoption.
>
> -- E
>
>>> On Mar 23, 2016, at 3:52 AM, Brent Royal-Gordon via swift-evolution
>>> <[email protected]> wrote:
>>>
>>> The solution is simple: allow trailing closures in guard bodies. This
>>> would allow this silly example to compile correctly:
>>>
>>> func f(arr : [Int]?) {
>>> guard let x = arr?.map {$0+1} else {
>>> preconditionFailure()
>>> }
>>>
>>> // ...
>>> }
>>
>> This sounds perfectly reasonable.
>>
>>> Alternatives considered
>>>
>>> There are three primary alternatives: do nothing, expand the scope of ‘if'
>>> and ‘while’ conditions as well, and significantly change the syntax of
>>> guard.
>>
>> A fourth alternative would be to change the syntaxes of `if` and `while`
>> (and probably `for` and `switch`) to also have a keyword in this position.
>>
>> if expr then { code }
>> while expr do { code }
>> for elem in expr do { code }
>> switch expr among { code }
>>
>> I'm not going to say I advocate for this option, but it *would* clearly mark
>> the end of the condition so that trailing closures could be brought to all
>> of these statements, so it seemed worth mentioning.
>>
>> --
>> Brent Royal-Gordon
>> Architechies
>>
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>
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