[swift-evolution] Add an ifPresent function to Optional

[Pierre Monod-Broca]

Kevin: +1

I don't know if it's relevant to put it in the standard library, but about the name : forSome would make more sense to me than forEach, or ifPresent

Pierre

> Le 12 mars 2016 à 17:32, Kevin Lundberg via swift-evolution <swift-evolution at swift.org> a écrit :
> 
> 
>> +1 -- I've used the "an optional is a collection with max 1 element" rhetoric to explain map/flatMap, would be great if this was true instead of "morally true".
> 
> If optional were a sequence or collection, then could if let be considered a special case for this?:
> 
> for x in optionalX {
> //...
> }
> 
> I do like the idea that optional could be considered a collection, but I also worry about confusion in this case:
> 
> let a: [Int]? = [1,2,3]
> 
> for x in a {
>  // a is [1,2,3], not the expected iteration of 1 through 3
> }
> 
> Today this does not compile and you are forced to unwrap the optional somehow. With this change I can see that someone may unexpectedly try this and be confused as to why the type of x is not what they expect. 
> 
>>> @Dave,Yes, CollectionType would be better than SequenceType.
>>> 
>>> On Saturday, 12 March 2016, Dave via swift-evolution<swift-evolution at swift.org(mailto:swift-evolution at swift.org)>wrote:
>>>> +1.
>>>> 
>>>> I’d go so far as to suggest that maybe Optional should conform to CollectionProtocol, since you can pretty easily think of an Optional as a collection that can’t have more than one element.
>>>> 
>>>> - Dave Sweeris
>>>> 
>>>>> On Mar 10, 2016, at 7:32 PM, Erica Sadun via swift-evolution<swift-evolution at swift.org(javascript:_e(%7B%7D,'cvml','swift-evolution at swift.org');)>wrote:
>>>>> 
>>>>> While I'm not convinced of the utility or lack thereof, wouldn't it make more sense
>>>>> to extend `forEach` to support optionals in a similar way that map and flapMap
>>>>> currently do rather than introduce `ifPresent`?
>>>>> 
>>>>> lety:Int? =1
>>>>> letn:Int? =nil
>>>>> 
>>>>> _=y.map({print($0) }) // works in current Swift
>>>>> _=n.map({print($0) }) // ditto
>>>>> 
>>>>> 
>>>>> y.forEach{ print($0) } // not currently a thing
>>>>> n.forEach{ print($0) } // ditto
>>>>> 
>>>>> Just spitballing here.
>>>>> 
>>>>> -- E
>>>>> 
>>>>> _______________________________________________
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>>> --
>>> -- Howard.
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