Re: [swift-evolution] IUO in Swift 3.0

[Joe Groff via swift-evolution]

> On Jun 22, 2016, at 1:03 PM, Chris Lattner  wrote:
> 
>> On Jun 22, 2016, at 8:56 AM, Joe Groff  wrote:
>>> I think that there is some confusion here: it is true that IUO exists 
>>> internally as a type within the compiler, but the idea of our current 
>>> implementation is that that is just an implementation detail within the 
>>> compiler (similar to LValueType, which has no user syntax), not an exposed 
>>> part of the programmer model.
>>> 
>>> That said, the “T!” *syntax* is intended to stay in Swift.  This is the way 
>>> to model the IUO declaration modifier, as outlined in the proposal.
>> 
>> As implemented in the seed, T! still leaks into the user type system.
> 
> Are there specific examples of that?  Those examples are bugs, that should be 
> fixed.
> 
> -Chris

var x = [Int!]()

-Joe
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Re: [swift-evolution] IUO in Swift 3.0

[Chris Lattner via swift-evolution]

> On Jun 22, 2016, at 8:56 AM, Joe Groff  wrote:
>> I think that there is some confusion here: it is true that IUO exists 
>> internally as a type within the compiler, but the idea of our current 
>> implementation is that that is just an implementation detail within the 
>> compiler (similar to LValueType, which has no user syntax), not an exposed 
>> part of the programmer model.
>> 
>> That said, the “T!” *syntax* is intended to stay in Swift.  This is the way 
>> to model the IUO declaration modifier, as outlined in the proposal.
> 
> As implemented in the seed, T! still leaks into the user type system.

Are there specific examples of that?  Those examples are bugs, that should be 
fixed.

-Chris
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Re: [swift-evolution] IUO in Swift 3.0

[Joe Groff via swift-evolution]

> On Jun 21, 2016, at 9:55 PM, Chris Lattner  wrote:
> 
> 
>> On Jun 21, 2016, at 1:39 PM, Jonathan Cotton via swift-evolution 
>>  wrote:
>> 
>> I was also surprised this type still exists as I'd taken that the proposal 
>> was for the removal of IUO as an explicit type, but after some testing of 
>> IUO propagation behaviour in Swift 3.0, I'm happy to report the behaviour 
>> has been changed to meet the desired behaviour in the spec, specifically, I 
>> now don't need to define a separate interface signature to specifically 
>> expect type T!
> 
> I think that there is some confusion here: it is true that IUO exists 
> internally as a type within the compiler, but the idea of our current 
> implementation is that that is just an implementation detail within the 
> compiler (similar to LValueType, which has no user syntax), not an exposed 
> part of the programmer model.
> 
> That said, the “T!” *syntax* is intended to stay in Swift.  This is the way 
> to model the IUO declaration modifier, as outlined in the proposal.

As implemented in the seed, T! still leaks into the user type system.

-Joe
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Re: [swift-evolution] IUO in Swift 3.0

[Chris Lattner via swift-evolution]

> On Jun 21, 2016, at 1:39 PM, Jonathan Cotton via swift-evolution 
>  wrote:
> 
> I was also surprised this type still exists as I'd taken that the proposal 
> was for the removal of IUO as an explicit type, but after some testing of IUO 
> propagation behaviour in Swift 3.0, I'm happy to report the behaviour has 
> been changed to meet the desired behaviour in the spec, specifically, I now 
> don't need to define a separate interface signature to specifically expect 
> type T!

I think that there is some confusion here: it is true that IUO exists 
internally as a type within the compiler, but the idea of our current 
implementation is that that is just an implementation detail within the 
compiler (similar to LValueType, which has no user syntax), not an exposed part 
of the programmer model.

That said, the “T!” *syntax* is intended to stay in Swift.  This is the way to 
model the IUO declaration modifier, as outlined in the proposal.

-Chris
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Re: [swift-evolution] IUO in Swift 3.0

[Jonathan Cotton via swift-evolution]

I was also surprised this type still exists as I'd taken that the proposal was 
for the removal of IUO as an explicit type, but after some testing of IUO 
propagation behaviour in Swift 3.0, I'm happy to report the behaviour has been 
changed to meet the desired behaviour in the spec, specifically, I now don't 
need to define a separate interface signature to specifically expect type T!

> On 21 Jun 2016, at 21:22, Joe Groff via swift-evolution 
>  wrote:
> 
> 
>> On Jun 21, 2016, at 1:06 PM, David Hart via swift-evolution 
>>  wrote:
>> 
>> Just saw this article about IUO in Swift 3.0:
>> 
>> https://www.bignerdranch.com/blog/wwdc-2016-increased-safety-in-swift-3/
>> 
>> I was surprised that the IUO type still exists. From what I understood, 
>> SE-0054 gives a clear example that:
>> 
>> func f() -> Int! { return 3 } 
>> // f: () -> Int?, has IUO attribute
>> // ...
>> 
>> let x3: Int! = f() 
>> // succeeds; x3: Int? = .some(3), has IUO attribute
>> // ...
>> 
>> func g() -> Int! { return nil } 
>> // f: () -> Int?, has IUO attribute
>> // ...
>> 
>> let y3: Int! = g() // succeeds; y3: Int? = .none, has IUO attribute
>> 
>> x3 and y3 should be a of type Int? but trying those out in Xcode 8’s beta 1 
>> playground show that they are still of type Int!. Did I miss something?
> 
> SE-0054 hasn't been fully implemented yet. The stricter implicit promotions 
> are mostly there, but the IUO type still exists.
> 
> -Joe
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Re: [swift-evolution] IUO in Swift 3.0

[David Hart via swift-evolution]

Is there a bug tracking the remaining part of the implementation?
Shouldn’t the proposal still be under “Not yet implemented” as its not 
completely implemented?

David.

> On 21 Jun 2016, at 22:22, Joe Groff  wrote:
> 
>> 
>> On Jun 21, 2016, at 1:06 PM, David Hart via swift-evolution 
>>  wrote:
>> 
>> Just saw this article about IUO in Swift 3.0:
>> 
>> https://www.bignerdranch.com/blog/wwdc-2016-increased-safety-in-swift-3/
>> 
>> I was surprised that the IUO type still exists. From what I understood, 
>> SE-0054 gives a clear example that:
>> 
>> func f() -> Int! { return 3 } 
>> // f: () -> Int?, has IUO attribute
>> // ...
>> 
>> let x3: Int! = f() 
>> // succeeds; x3: Int? = .some(3), has IUO attribute
>> // ...
>> 
>> func g() -> Int! { return nil } 
>> // f: () -> Int?, has IUO attribute
>> // ...
>> 
>> let y3: Int! = g() // succeeds; y3: Int? = .none, has IUO attribute
>> 
>> x3 and y3 should be a of type Int? but trying those out in Xcode 8’s beta 1 
>> playground show that they are still of type Int!. Did I miss something?
> 
> SE-0054 hasn't been fully implemented yet. The stricter implicit promotions 
> are mostly there, but the IUO type still exists.
> 
> -Joe

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Re: [swift-evolution] IUO in Swift 3.0

[Jonathan Cotton via swift-evolution]

I was also surprised this type still exists as I'd taken that the proposal was 
for the removal of IUO as an explicit type, but after some testing of IUO 
propagation behaviour in Swift 3.0, I'm happy to report the behaviour has been 
changed to meet the desired behaviour in the spec, specifically, I now don't 
need to define a separate interface signature to specifically expect type T!

> On 21 Jun 2016, at 21:22, Joe Groff via swift-evolution 
>  wrote:
> 
> 
>> On Jun 21, 2016, at 1:06 PM, David Hart via swift-evolution 
>>  wrote:
>> 
>> Just saw this article about IUO in Swift 3.0:
>> 
>> https://www.bignerdranch.com/blog/wwdc-2016-increased-safety-in-swift-3/
>> 
>> I was surprised that the IUO type still exists. From what I understood, 
>> SE-0054 gives a clear example that:
>> 
>> func f() -> Int! { return 3 } 
>> // f: () -> Int?, has IUO attribute
>> // ...
>> 
>> let x3: Int! = f() 
>> // succeeds; x3: Int? = .some(3), has IUO attribute
>> // ...
>> 
>> func g() -> Int! { return nil } 
>> // f: () -> Int?, has IUO attribute
>> // ...
>> 
>> let y3: Int! = g() // succeeds; y3: Int? = .none, has IUO attribute
>> 
>> x3 and y3 should be a of type Int? but trying those out in Xcode 8’s beta 1 
>> playground show that they are still of type Int!. Did I miss something?
> 
> SE-0054 hasn't been fully implemented yet. The stricter implicit promotions 
> are mostly there, but the IUO type still exists.
> 
> -Joe
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Re: [swift-evolution] IUO in Swift 3.0

[Joe Groff via swift-evolution]

> On Jun 21, 2016, at 1:06 PM, David Hart via swift-evolution 
>  wrote:
> 
> Just saw this article about IUO in Swift 3.0:
> 
> https://www.bignerdranch.com/blog/wwdc-2016-increased-safety-in-swift-3/
> 
> I was surprised that the IUO type still exists. From what I understood, 
> SE-0054 gives a clear example that:
> 
> func f() -> Int! { return 3 } 
> // f: () -> Int?, has IUO attribute
> // ...
> 
> let x3: Int! = f() 
> // succeeds; x3: Int? = .some(3), has IUO attribute
> // ...
> 
> func g() -> Int! { return nil } 
> // f: () -> Int?, has IUO attribute
> // ...
> 
> let y3: Int! = g() // succeeds; y3: Int? = .none, has IUO attribute
> 
> x3 and y3 should be a of type Int? but trying those out in Xcode 8’s beta 1 
> playground show that they are still of type Int!. Did I miss something?

SE-0054 hasn't been fully implemented yet. The stricter implicit promotions are 
mostly there, but the IUO type still exists.

-Joe
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[swift-evolution] IUO in Swift 3.0

[David Hart via swift-evolution]

Just saw this article about IUO in Swift 3.0:

https://www.bignerdranch.com/blog/wwdc-2016-increased-safety-in-swift-3/

I was surprised that the IUO type still exists. From what I understood, SE-0054 

 gives a clear example that:

func f() -> Int! { return 3 } // f: () -> Int?, has IUO attribute
// ...
let x3: Int! = f() // succeeds; x3: Int? = .some(3), has IUO attribute
// ...
func g() -> Int! { return nil } // f: () -> Int?, has IUO attribute
// ...
let y3: Int! = g() // succeeds; y3: Int? = .none, has IUO attribute

x3 and y3 should be a of type Int? but trying those out in Xcode 8’s beta 1 
playground show that they are still of type Int!. Did I miss something?

David.___
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