<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 Feb 8, 2017, at 12:18 AM, Jacob Bandes-Storch via swift-dev <<a href="mailto:swift-dev@swift.org" class="">swift-dev@swift.org</a>> wrote:</div><div class=""><div dir="ltr" class="">I don't think it would be a very big parser change to invert the relationship. Maybe I'll try it out and put up another PR.</div></div></blockquote><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><br class=""></div><div class="">On the other hand, noticed the header comment says:</div><div class=""><br class=""></div><div class=""><div class="">/// ...Because the capture list is evaluated outside of the closure, this</div><div class="">/// CaptureList wraps the ClosureExpr. The dynamic semantics are that evaluates</div><div class="">/// the variable bindings from the capture list, then evaluates the</div><div class="">/// subexpression (the closure itself) and returns the result.</div></div></div></div></blockquote><div><br class=""></div>I think the original representation just made the captures part of the ClosureExpr, and IIRC Chris changed it to this intentionally. I don't remember why; maybe it was causing problems for some tooling that wanted to walk the expression tree and find uses of the variable? It's certainly kindof weird for IRGen.</div><div><br class=""></div><div>John.</div><div><br class=""></div><div><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><div class=""><br class=""></div><div class="">🤷‍<br class=""></div><div class="gmail_extra">
<br class=""><div class="gmail_quote">On Tue, Feb 7, 2017 at 9:10 PM, Slava Pestov <span dir="ltr" class=""><<a href="mailto:spestov@apple.com" target="_blank" class="">spestov@apple.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="word-wrap:break-word" class=""><br class=""><div class=""><span class="gmail-"><blockquote type="cite" class=""><div class="">On Feb 7, 2017, at 9:09 PM, Jacob Bandes-Storch <<a href="mailto:jtbandes@gmail.com" target="_blank" class="">jtbandes@gmail.com</a>> wrote:</div><br class="gmail-m_-7115685859560707654Apple-interchange-newline"><div class=""><div dir="ltr" class="">PR'd: <a href="https://github.com/apple/swift/pull/7326" target="_blank" class="">https://github.com/apple/<wbr class="">swift/pull/7326</a><div class=""><br class=""></div><div class="">Although I would also ask: why is CaptureListExpr a <b class="">parent</b> of ClosureExpr and not a child?</div></div></div></blockquote><div class=""><br class=""></div></span>I think it’s kind of arbitrary. You could also argue that they should be one and the same AST node. I think right now it’s just a property of how the parser works, the capture list comes first, before the closure body?</div><span class="gmail-HOEnZb"><font color="#888888" class=""><div class=""><br class=""></div><div class="">Slava</div></font></span><span class="gmail-"><div class=""><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_extra"><br clear="all" class=""><div class=""><div class="gmail-m_-7115685859560707654gmail_signature"><div dir="ltr" class=""><div class="">Jacob<br class=""></div></div></div></div>
<br class=""><div class="gmail_quote">On Tue, Feb 7, 2017 at 7:56 PM, Slava Pestov <span dir="ltr" class=""><<a href="mailto:spestov@apple.com" target="_blank" class="">spestov@apple.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="word-wrap:break-word" class=""><br class=""><div class=""><span class=""><blockquote type="cite" class=""><div class="">On Feb 7, 2017, at 7:30 PM, Jacob Bandes-Storch via swift-dev <<a href="mailto:swift-dev@swift.org" target="_blank" class="">swift-dev@swift.org</a>> wrote:</div><br class="gmail-m_-7115685859560707654m_-1882571583119174456Apple-interchange-newline"><div class=""><div dir="ltr" class="">I just learned about CaptureListExpr when working on some diagnostics. Is there a particular reason that its member "closureBody" is an Expr* and not a ClosureExpr*? There seems to be <a href="https://github.com/apple/swift/blob/1e46f13184d7256c991b2ba9424af9efe3cd860f/lib/Parse/ParseExpr.cpp#L2425" target="_blank" class="">only one place it's built</a>, and the body is always a ClosureExpr.<div class=""><br class=""></div><div class="">I can see <a href="https://github.com/apple/swift/blob/1e46f13184d7256c991b2ba9424af9efe3cd860f/lib/AST/ASTWalker.cpp#L663-L665" target="_blank" class="">one minor place</a> where it might be less convenient to have a ClosureExpr, but otherwise there doesn't seem to be much of a reason to keep it generalized to Expr*.</div></div></div></blockquote><div class=""><br class=""></div></span>Since autoclosures cannot have capture lists, I think the change you’re suggesting makes sense.</div><div class=""><br class=""></div><div class="">Slava</div><div class=""><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><div class=""><br clear="all" class=""><div class=""><div class="gmail-m_-7115685859560707654m_-1882571583119174456gmail_signature"><div dir="ltr" class=""><div class="">Jacob<br class=""></div></div></div></div>
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