[swift-evolution] Proposal: Add "none" and simplify the language.

[Amir Michail]

> On Jan 7, 2016, at 2:09 PM, Félix Cloutier <felixcca at yahoo.ca> wrote:
> 
> That would leave you with runtime checks instead of compile-time checks and I totally disagree with that.
> 

Implicitly unwrapped optionals do runtime checks also.

> Félix
> 
>> Le 7 janv. 2016 à 13:45:21, Amir Michail <a.michail at me.com <mailto:a.michail at me.com>> a écrit :
>> 
>> 
>>> On Jan 7, 2016, at 1:40 PM, Félix Cloutier <felixcca at yahoo.ca <mailto:felixcca at yahoo.ca>> wrote:
>>> 
>>> An implicitly-unwrapped optional would do almost that, no?
>>> 
>> 
>> You can use “none” to eliminate implicitly unwrapped optionals from the language.
>> 
>>> Félix
>>> 
>>>> Le 7 janv. 2016 à 12:46:53, Amir Michail via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> a écrit :
>>>> 
>>>> Examples:
>>>> 
>>>> var x:Int = none // uninitialized but not an optional
>>>> 
>>>> print(x) // run-time error as x is uninitialized
>>>> 
>>>> if x == nil { … } // compile time error… x can never be nil because it is not an optional
>>>> 
>>>> if x == none { x = 2 } // … but it can be uninitialized
>>>> 
>>>> Optionals can also be uninitialized:
>>>> 
>>>> var y:Int? = none // uninitialized and an optional
>>>> 
>>>> if y == nil { … } // run-time error as y is uninitialized
>>>> 
>>>> y = nil
>>>> 
>>>> if y == nil { … } // fine
>>>> 
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>>> 
>> 
> 

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