> On Jun 12, 2017, at 3:13 PM, Jens Persson <j...@bitcycle.com> wrote:
> On Mon, Jun 12, 2017 at 8:52 PM, John McCall <rjmcc...@apple.com
> <mailto:rjmcc...@apple.com>> wrote:
>
> We really do want to tie most of these features specifically to function
> calls.
>
>
> I'm not sure if I understand what you mean. Do you mean that you really don't
> want these features to require changes to the type system?
That's correct. There's a lot of special structure to function calls — labels,
overloading, default arguments, variadics, inout arguments, (eventually)
borrowed arguments — that we do not want to introduce into the first-class
tuple system, or at least not in the exact same way. In some cases, like
overloading or defaulted and inout arguments, it cannot be done without a major
and unwanted model shift. In other cases, like variadics, it could
theoretically be done but would complicate the type system in ways we are
trying to avoid.
Regardless, the existence of any call-specific structure at all implies that
generic value forwarding cannot always be sufficient to do generic argument
forwarding. Maybe that's an argument for not having any call-specific
structure, but we do have that and it's not going away.
John.
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