> On Sep 25, 2017, at 14:37, Joe Groff <jgr...@apple.com> wrote: > > > >> On Sep 23, 2017, at 10:36 PM, Robert Widmann via swift-dev >> <swift-dev@swift.org> wrote: >> >> Why is the arrow carrying the “Has Value Semantics Bit” rather than it being >> part of a protocol composition on an argument type, or a convention bit on >> the parameter like ‘inout’? > > Value semantics is a property of operations, not really of types. I would say > the function arrow is the right place for it, since not-value-semantics > propagates in the same manner as an effect like "throws". Dave, you might in > fact look at how 'throws' type checking is implemented as a model for what > you're trying to do.
Hi Joe, In fact, I tried to replicate the “closureCanThrow()” logic before emailing this list, but that didn’t work due to a chicken-and-egg problem that arrises between when a ClosureExpr's body is type checked and knowing the type of the ClosureExpr. In other words, a closure has value semantics iff all operations within it have value semantics. As I wrote earlier in this email thread, the “value semantics” implementation I’m working on is sufficient for the research that I’m doing. That being said, I took some shortcuts to get it working and the closure type shortcut bothered me the most. That is why I emailed this list about how to propagate the contextual ExtInfo bit onto the closure type. Based on John’s helpful email, I think I’ll just live with the shortcuts I made for now. Thanks, Dave _______________________________________________ swift-dev mailing list swift-dev@swift.org https://lists.swift.org/mailman/listinfo/swift-dev
