<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div><blockquote type="cite" class=""><div class="">On Jun 12, 2017, at 3:13 PM, Jens Persson <<a href="mailto:jens@bitcycle.com" class="">jens@bitcycle.com</a>> wrote:</div><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote">On Mon, Jun 12, 2017 at 8:52 PM, John McCall <span dir="ltr" class=""><<a href="mailto:rjmccall@apple.com" target="_blank" class="">rjmccall@apple.com</a>></span> wrote:<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class=""><div class=""><span class=""><div class=""><br class=""></div></span>We really do want to tie most of these features specifically to function calls.</div></div></blockquote><div class=""><br class=""></div><div class=""><br class=""></div><div class="">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?</div></div></div></div></div></blockquote><div><br class=""></div>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.</div><div><br class=""></div><div>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.</div><div><br class=""></div><div>John.</div></body></html>