If inference only works in simple cases, I think it would seem like it works
unpredictability to anyone unfamiliar with the implementation details.
I image the question of "why do I have to declare a type here, but not in this
case?" coming up.
Declaring types is one of the first things you have to learn anyway. Just
declaring a function already requires some understanding of types. Properties
are not much different IMO.
> On 8 Apr 2017, at 08:34, Brent Royal-Gordon via swift-evolution
> <swift-evolution@swift.org> wrote:
>
>> On Apr 7, 2017, at 12:21 AM, Daniel Duan via swift-evolution
>> <swift-evolution@swift.org> wrote:
>>
>> The cons for doing this are obvious too: the inference makes the language
>> feels more friendly and is, undoubtedly, a beloved feature for many. This
>> would be a source breaking change.
>
>
> Beyond just being more friendly, I think it could be considered a teaching
> issue. A great way to introduce beginners to custom types would be something
> like:
>
> struct Point {
> var x = 0.0
> var y = 0.0
> }
>
> Or:
>
> struct Person {
> var name = ""
> var age = 18
> }
>
> If you have to explicitly specify types for the properties, that's another
> thing you need to introduce to people before you can do this.
>
> On the other hand, a very limited form of inference might be fine here.
> Imagine if we did a sort of limited, single-pass, top-down inference which
> only understood a few things (literals, tuple syntax, initializer calls),
> stopped once it had seen enough to infer a complete type, and rejected an
> expression if it encountered something it didn't understand before finishing.
> That would probably cover most simple cases, and it would probably only allow
> expressions whose types were obvious enough that we could use it for
> arguments, too. (But of course it would mean more code in the compiler, so it
> might not be worth it.)
>
> --
> Brent Royal-Gordon
> Architechies
>
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