> On Nov 10, 2017, at 10:41 AM, Chris Lattner <sa...@nondot.org> wrote: > > On Nov 10, 2017, at 10:03 AM, Joe Groff <jgr...@apple.com> wrote: >> >> I don't like the idea of some calls having wildly different semantics from >> others; it's difficult enough to tell what exactly a call might be doing >> already. > > This isn’t particularly useful feedback. Can you elaborate more on what your > concern is, and how calls are unlike anything else in Swift that would have > this potential problem? > >> Since we also lack the more obvious static "Callable" protocol idea to give >> even well-typed call syntax to user-defined types, this also seems like it'd >> be easily abused for that purpose too. > > Similarly, I’d love for you to elaborate on how the potential for abuse of > this feature is different than anything else in Swift (e.g. operator > overloading). Potential for abuse hasn’t been a particularly guiding force > in the design on Swift, and for good reasons. > > I also don’t understand what you mean by a static Callable protocol. I > specifically address what I think you might mean in the “alternatives” part > of the proposal, did you read that?
People have reasonably asked for the ability to make their own function-like types in the past, such that "myvalue(...)" behaves like sugar for "myvalue.call(...)" or something like that. In most cases, they still want to have type system control over what arguments and results their call operation produces. They don't really get that with this proposal; they lose all control over the arity and argument types. That may be what you want for calling into a dynamically-typed black hole, but it's not what you want in general. I fear that people would be willing to compromise their designs in order to get the sugar they want by contorting to fit this design. > >> I think a much better general solution to the problem of "make dynamic >> systems interact with type systems" is something like F#'s type providers >> which lets you write your own importers that look at dynamic information >> from a database, dynamic language VM, or some other system and generate type >> information usable by the compiler. > > Thanks! I wasn’t aware of type providers, I’ll investigate them. > >> Integration at the importer level could let you produce more well-typed >> Swift declarations by looking at the runtime information you get by >> importing a Python module. > > This is also addressed directly in the proposal. I don’t want to add Python > specific support to Swift. The motivations are explained in the proposal. I'm not suggesting a Python-specific feature, I'm suggesting that type providers could be a general framework for the kinds of problems you encounter trying to make dynamic systems work with Swift, including Python. -Joe _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
