Supporting Extensions for Structural Types

[David_Sweeris]

@eaplatanios

Thanks @Fryie! I agree with you. In this case, it would be great if someone could answer the following couple questions:

1. What is it that makes extending tuples hard right now? Why are tuples not represented as structs?
2. What would it take to add support for this feature, without worrying about variadic generics for now? Are there some good starting points about where to look and what needs to change?

I don't know if things have changed in the he intervening year and a half, but back in Nov of 2017 @John_McCall made a couple of posts that partially answers your questions. They're both from the same thread so the forum software names them the same, but these two links really are different

1. Synthesizing Equatable, Hashable, and Comparable for tuple types - #63 by John_McCall
2. Synthesizing Equatable, Hashable, and Comparable for tuple types - #65 by John_McCall

Assuming nothing has changed WRT this in the past year and a half, the notable quote relevant to this thread is, "I think it would be difficult to allow useful user-defined extensions/conformances of arbitrary tuple types without variadic generics". I'd love to know if he (or anyone else who's sufficiently familiar with the compiler) thinks this is still the case.

IIRC @Douglas_Gregor is (or at least was at one point) the generics guy, so maybe he has thoughts on the matter as well.