[swift-evolution] [Idea] Find alternatives to `switch self`

[Charles Constant]

Good grief. I think you're right.

Some how, a long time ago, I got it into my head that the order in which
each part of the ternary got evaluated would cause problems for this kind
of thing.

I've had a huge blindspot and I've been railing on the list for something I
don't need for weeks.

Wow, I couldn't be more embarassed.

But I'm happy too, because I can go ahead and just use a chained ternary.

Sorry all, and thanks.


On Mon, May 23, 2016 at 6:26 PM, Dany St-Amant <dsa.mls at icloud.com> wrote:

>
> Le 20 mai 2016 à 07:14, Charles Constant via swift-evolution <
> swift-evolution at swift.org> a écrit :
>
> I wrote some code tonight to experiment with this kind of thing. I
> apologize if it's off-topic for the thread, but it might be useful to
> others who want to experiment.
>
>
>
> //: Playground - noun: a place where people can play
>
> import Cocoa
>
> infix operator • { precedence 180 }
> infix operator → { associativity left precedence 70 }
> infix operator … { associativity right precedence 60 }
>
> func → <T>( lhs: Bool, rhs: T ) -> T? {
> return lhs ? rhs : nil
> }
>
> func … <T>( lhs:T?, rhs:T ) -> T {
> return lhs != nil ? lhs! : rhs
> }
>
> func depends<I,O>( dep:I, _ closure: (I)->(O) ) -> O {
> return closure( dep )
> }
>
> func • <I,O>( lhs: I, rhs: (I)->(O) ) -> O {
> return depends( lhs, rhs )
> }
>
> /* Example using "depends" */
>
> let
> str:String,
> i = 7
>
> str = depends( i ){
> $0==2 → "two" …
> $0==3 → "three" …
> $0==4 → "four" …
> "other"
> }
>
>
> Hmm… replacing -> by ?, and … by : you get:
>
> str = depends( i ){
>     $0==2 ? "two" :
>     $0==3 ? "three" :
>     $0==4 ? "four" :
>     "other"
> }
>
> which work as is without a need to define new operators.
>
> Dany
>
> /* Example using "•" operator as "depends" */
>
> enum People { case Kurtz, Popescu, Lime, Martins }
> enum Order { case First, Second, Third, Unknown }
>
> let
> order:Order,
> person:People = .Lime
>
> order = person • {
> $0 == .Kurtz → .First …
> $0 == .Popescu → .Second …
> $0 == .Lime → .Third …
> .Unknown
> }
>
>
> I also have some trepidation about posting it here, because it might have
> bugs. I wans't sure what "precedence" and "associativity" should be, for
> example. But it does make it more convenient to test alternative characters
> for operators, etc.
>
>
>
>
>
>
>
>
>
>
>
> On Sat, Apr 9, 2016 at 12:05 AM, Vladimir.S via swift-evolution <
> swift-evolution at swift.org> wrote:
>
>>
>> On 09.04.2016 9:31, Brent Royal-Gordon wrote:
>>
>>> This design is still very much under development—it hasn't even been
>>> reviewed, let alone added to the language. Here's the draft proposal:<
>>> https://github.com/jtbandes/swift-evolution/blob/case-enumerable/proposals/0000-derived-collection-of-enum-cases.md
>>> >
>>>
>>> I'm not saying that this will necessarily be a solution that ends up
>>> being accepted—I'm merely saying that yes, it's something people are
>>> thinking about and designing; it's just been inactive for a few weeks.
>>>
>>
>> Oh, I see. Thank you for letting know. Just missed "you would be able" in
>> your previous message, did read it as "you are able", so was trying to find
>> this in current Swift version. OK, glad to know that most likely we'll have
>> improvements in enums eterations for Swift 3.0.
>>
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>>
>
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