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

[Amir Michail]

Sent from my iPad

> On Jan 7, 2016, at 2:34 PM, Félix Cloutier <felixcca at yahoo.ca> wrote:
> 
> Yes, but following your suggestion, there may not be a difference between a non-optional value and an implicitly-wrapped optional, meaning that there will be a lot more of them.

Variables that are never assigned "none" need not have these runtime checks. Alternatively, you can have a type suffix similar to ? to indicate that a variable may be in an uninitialized state. 

> 
> Félix
> 
>>> Le 7 janv. 2016 à 14:10:44, Amir Michail <a.michail at me.com> a écrit :
>>> 
>>> 
>>> 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> a écrit :
>>>>> 
>>>>> 
>>>>> On Jan 7, 2016, at 1:40 PM, Félix Cloutier <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> 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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