[swift-evolution] [Pitch] Remove type-inference for stored property

[Jean-Daniel]

I’m full -1 on this one. It will make the language inconsistent. How do you explain a new comer that type inference work in some case, but not in other cases, while in both the compiler is completely capable to define the type.

Why 

let myString = "hello" 

would be accepted but not 

class Foo {
	let myString = "hello" 
}



> Le 10 avr. 2017 à 04:05, Daniel Duan via swift-evolution <swift-evolution at swift.org> a écrit :
> 
> I’m still not sure whether *I* want this. But here’s a proposal anyways: https://gist.github.com/dduan/5017a0b0f0880d014f4ce14c4ca7fb55 <https://gist.github.com/dduan/5017a0b0f0880d014f4ce14c4ca7fb55>
> 
>> On Apr 7, 2017, at 12:21 AM, Daniel Duan via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
>> Hi all,
>> 
>> In a discussion about inferring parameter types from default value, Slava brought up some performance problems caused by type inference for stored properties in side types:
>> 
>> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20170313/033882.html <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20170313/033882.html>
>> 
>> Towards the end, the post mentioned that some Swift team members contemplated requiring types for stored properties in type declarations. I think this idea deserves some more attention. Hence this last minute idea-floating.
>> 
>> In addition to solving a performance headache in implementation, there're always the general benefit of making type declartion more explicit and readable (clarity for reader should out-weigh pleasure of the author). Making the
>> language slightly more consistent (we are not inferring types for default parameter values in function anyways).
>> 
>> 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.
>> 
>> Just thought I'd float the idea to gather some quick reaction. What do y'all think?
>> 
>> Daniel Duan
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