[swift-evolution] ternary operator ?: suggestion

[Sean Heber]

Could alternatively could take a page from Smalltalk:

   extension Bool {
      func ifTrue<T>(@autoclosure isTrue: () -> T, @autoclosure otherwise isFalse: () -> T) -> T {
         if self {
            return isTrue()
         } else {
            return isFalse()
         }
      }
   }

:)

l8r
Sean


> On Dec 4, 2015, at 1:40 AM, David Waite <david at alkaline-solutions.com> wrote:
> 
> Of course one could just drop it as a grammatical language feature and turn it a standard library feature of some form, e.g.:
> 
> @warn_unused_result
> func when<T>(@autoclosure expr: ()->Bool, @autoclosure value: ()->T, @autoclosure otherwise: ()->T) -> T {
>   if expr() {
>     return value()
>   }
>   else {
>     return otherwise()
>   }
> }
> 
> var a = when(1 + 1 == 2, value: "works", otherwise: "fails")
> 
> print(a) // => “works"
> 
> -DW
> 
>> On Dec 4, 2015, at 12:26 AM, David Hart <david at hartbit.com> wrote:
>> 
>> I also tend to agree but I don't like the ordering in the Python version and would rather see the introduction of the then keyword
>> 
>> On 04 Dec 2015, at 06:08, Sean Heber <sean at fifthace.com> wrote:
>> 
>>> I agree that using ? for ternary feels.. uncomfortable in Swift. I wouldn't mind seeing Python-style or just eliminating it entirely in favor of simplicity.
>>> 
>>> l8r
>>> Sean
>>> 
>>> On Dec 3, 2015, at 10:48 PM, Dan Appel <dan.appel00 at gmail.com> wrote:
>>> 
>>>> I agree that ternary can make code unreadable, especially so with the ‘?’. I personally like the Haskel option the most, but it introduces a new keyword ‘then’, which isn’t great either. Python’s "y if x else z" is therefore, in my opinion, the best alternative.
>>>> 
>>>> Also, I found it interesting how split the Rust community was about removing the ternary operator.
>>>> 
>>>> — 
>>>> Dan Appel
>>>> 
>>>> On Thu, Dec 3, 2015 at 7:58 PM J. Cheyo Jimenez <cheyo at masters3d.com> wrote:
>>>> Would you consider replacing the C style ?: ternary operator to something that does not use the question mark and colon ? 
>>>> 
>>>> The use of "?" can be confusing when speed reading code with optionals. 
>>>> 
>>>> Consider this code as somebody learning swift as their first language.
>>>> let result = !condition ? 1 : 2
>>>> 
>>>> 
>>>> Some alternatives:
>>>> 
>>>> Haskel 
>>>> if predicate then expr1 else expr2
>>>> Python
>>>> result = x if a > b else y
>>>> The advantage of not using the question mark is that the language will be more consistency on the use of "?" to mean only optionals. 
>>>> 
>>>> 
>>>> References:
>>>> https://devforums.apple.com/message/1020139#1020139
>>>> https://github.com/rust-lang/rust/issues/1698#issuecomment-3705066
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