[Second review] SE-0453: Vector, a fixed size array

[ksluder (Kyle Sluder)]

A few people brought up tuples in the original discussion, including myself:

@ksluder

Endowing tuples with the ability to describe repeated elements would also give the language a way to describe the memory layout of any nominal type, including classes:

But @scanon enumerated several reasons why this approach was not taken:

@scanon

• Tuples are non-nominal types, so there's no way to conform them to, say Collection.
• Tuple conformances can only express the special case of a tuple that conforms to a protocol because all of its elements do.
• The ABI mangling for tuples is pretty awful when it comes to using them as a fixed-size container.
• We have no good mechanism for talking about large homogeneous tuples in the language.
• Plumbing initialization through tuples is kind of a mess.
• Also there's a layout issue about tail padding.
• and some other stuff

I still think the right approach is to resolve these issues instead of introducing a new language construct that models a precise subset of tuple functionality. Even with an ideal name that everyone could agree to, the existence of this new type will forever present the question of which to use in any given situation. The language is conceptually leaner with a single tuple type.

Is it at all feasible to name this type Tuple and commit to the eventual goal of making it the nominal generic supertype of all tuples?