[swift-evolution] [Proposal Draft] Literal Syntax Protocols

[Dave Abrahams]

on Tue Jun 28 2016, Sean Heber <swift-evolution at swift.org> wrote:

> Arg. Dang it!
>
> Syntax.ExpressibleAsIntegerLiteral

+1

IMO it's not possible to improve on that one.

> Syntax.FromIntegerLiteral
> Syntax.IntegerLiteralManifestation
> Syntax.GhostOfIntegerLiteral
> Syntax.FormerlyKnownAsIntegerLiteral
>
> l8r
> Sean 
>
> Sent from my iPad
>
> On Jun 28, 2016, at 10:29 PM, Erica Sadun <erica at ericasadun.com> wrote:
>
>>> On Jun 28, 2016, at 9:21 PM, Sean Heber <sean at fifthace.com> wrote:
>>> 
>>> IntegerLiteralExpressable?
>>> 
>>> Does Apple employ any philosophers? We might need one...
>>> 
>>> l8r
>>> Sean
>>> 
>> 
>> Aaaaaand...welcome to last night.
>> 
>> The problem being, that people see this and think that the type can be
>> expressed as an integer literal, not that an integer literal can be expressing
>> the type. (I won't even bring up other associations for that word since
>> most of the subscribers of this mailing list have not been nursing mothers
>> although some may be familiar with the technique.)
>> 
>> -- E
>> 
>> 
>>> 
>>>> On Jun 28, 2016, at 10:02 PM, Erica Sadun <erica at ericasadun.com> wrote:
>>>> 
>>>> 
>>>>> On Jun 28, 2016, at 8:08 PM, Sean Heber <sean at fifthace.com> wrote:
>>>>> 
>>>>> What about..
>>>>> 
>>>>> Syntax.ConvertibleFromIntegerLiteral
>>>>> etc..
>>>> 
>>>> I like it but Dave has already expressed that this isn't conversion. This
>>>> is something distinct, magical, and more importantly, ineffable.
>>>> 
>>>> He says it means an instance of the type can be written as a literal, and
>>>> not converted from a literal. He writes:
>>>> 
>>>>> Conformance to this protocol does *not* mean you can initialize the type with
>>>>> a literal. 
>>>>> 
>>>>> Proof:
>>>>> 
>>>>> func f<T: IntegerLiteralConvertible>() -> T {
>>>>> return T(integerLiteral: 43) // Error
>>>>> return T(43)                 // Also an Error
>>>>> }
>>>>> 
>>>>> It means an instance of the type can be *written* as a literal:
>>>>> 
>>>>> func f<T: IntegerLiteralConvertible>() -> T {
>>>>> return 43   // OK
>>>>> }
>>>>>> 
>>>> 
>>>> So we're looking at something more like:
>>>> 
>>>> Syntax.AnIntegerLiteralCanBeSubstitutedForThisTypeAndTheCompilerWillNotBarf
>>>> 
>>>> -- E
>>>> 
>>>> 
>> 
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-- 
Dave