[swift-evolution] ternary operator ?: suggestion

[Kevin Lundberg]

Ostensibly, case may not be necessary if you could delimit each case on one line with something (perhaps a comma, or something else if that would not fit well within the grammar):

let thisColor = thatColor ? .Blue: .Red, .Green: .Blue, .Red: .Green,
default: .Yellow

On Sun, Dec 6, 2015, at 01:57 PM, Paul Ossenbruggen via swift-evolution wrote:
> I like this too, seems more powerful.  Also, would single line
> expressions be allowed?  If not would case be required for example:
>
> let myFavoriteColor = yourFavoriteColor ?    case .Blue: .Red    case
> .Green: .Blue    case .Red: .Green    default: .Yellow
>
>
>> On Dec 6, 2015, at 9:11 AM, Sean Heber via swift-evolution <swift-
>> evolution at swift.org> wrote:
>>
>> I really like this train of thought. +1
>>
>> l8r Sean
>>
>> On Dec 6, 2015, at 11:02 AM, Alex Lew via swift-evolution <swift-
>> evolution at swift.org> wrote:
>>> What if we left the if { ...} else { ... } syntax alone (as a
>>> statement), and updated the ternary expression to be a more general
>>> pattern matching expression (closer to "switch")? Something like
>>>
>>> let x = condition ?   true: "Hello"   false: "Goodbye"
>>>
>>> let x = optionalValue ?   .Some(let unwrapped): "Hello,
>>> \(unwrapped)"   .None: "To Whom It May Concern"
>>>
>>> let myFavoriteColor = yourFavoriteColor ?    .Blue: .Red    .Green:
>>> .Blue    .Red: .Green
>>>
>>> let quadrant = (x, y) ?    let (x, y) where x < 50 && y < 50: "top
>>> left"    let (x, y) where x < 50 && y > 50: "bottom left"    let (x,
>>> y) where x > 50 && y < 50: "top right"    default: "bottom right"
>>>
>>> The colon comes from the fact that this is sort of a light-weight
>>> expression-based "switch" statement, where each branch can only
>>> contain an expression, not a series of statements.
>>>
>>> This is very similar to pattern matching expressions in languages
>>> like Haskell, ML, and Coq.
>>>
>>> On Sun, Dec 6, 2015 at 11:25 AM, Thorsten
>>> Seitz<thorsten.seitz at web.de>wrote:
>>>>
>>>>> Am 06.12.2015 um 01:28 schrieb Alex Lew via swift-evolution <swift-
>>>>> evolution at swift.org>:
>>>>>
>>>>> I don't think you can just get rid of the if statement in favor of
>>>>> an expression. You still want to be able to do this:
>>>>>
>>>>> if (condition) {    funcWithSideEffectsThatReturnsInt() } else {
>>>>> funcWithSideEffectsThatReturnsString() }
>>>>>
>>>>> but that's not a valid expression (what is its type?).
>>>>
>>>>
>>>> That would actually be no problem if Swift’s type system would have
>>>> union types (Ceylon has union and intersection types which are
>>>> quite awesome and enable lots of nice things quite naturally, see
>>>> http://ceylon-lang.org/documentation/1.2/tour/types/).
>>>>
>>>> In that case the type of such an expression would just be the union
>>>> of both types, which is writtenInt | Stringin Ceylon.
>>>>
>>>>
>>>> -Thorsten
>>>>
>>>>
>>>
>>>
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