Supporting Extensions for Structural Types

[taylorswift]

@Jon_Hull

The '...' signifies an arbitrary number of slots of whatever was in the slot before it (in this case T).

If we wanted, you could potentially have other types in the tuple around it, I suppose:

(Int, T, ...) //1 int slot followed by an arbitrary number of T

to try and get this conversation away from syntax and back to semantics, i just wanna point to what my vector manifesto writeup has to say about this issue, and that’s that if you want to have “an arbitrary number of T” (as opposed to “an arbitrary number of arbitrary types T), you’re probably going to want to parameterize that quantity in the form of a generic multiplicity parameter/associated concept. This is the whole idea around having GMPs.

protocol HomogenousTuple
{
    associatedtype Element 
    associatedmultiplicity N

    init(headerAndElements:(Int, Element * N))
}

struct S:Homogenous3Tuple<Element>:HomogenousTuple
{
    init(headerAndElements:(Int, Element, Element, Element)) 
    {
        ...
    }
}