on Fri May 13 2016, Joe Groff <[email protected]> wrote: >> On May 13, 2016, at 9:13 AM, Rob Napier via swift-evolution >> <[email protected]> wrote: >> >> Currently if a closure takes a value, it requires "_ in" to note >> that the value is ignored. This makes sense in many cases, but >> creates a bit of a mess in the case of an empty, void-returning > >> closure: >> >> doThing(withCompletion: { _ in }) >> >> I'd like to suggest that the compiler promote the empty closure >> literal {} to any void-returning closure type so that this could be >> written: >> >> doThing(withCompletion: {}) >> >> This encourages the use of empty closures over optional closures, >> which I think is open for debate. In general I try to avoid >> optionals when they can be precisely replaced with a non-optional >> value. Furthermore, most Cocoa completion handlers are not optional. >> >> The alternative is to not do this, but encourage that any closure >> that could reasonably be empty should in fact be optional. I would >> then want Cocoa functions with void-returning closures to be >> imported as optionals to avoid "{ _ in }". > > +1. In general, I think we should allow implicit arguments, without > requiring the closure to use all the implicit $n variables like we do > today. These should all be valid: > > let _: () -> () = {} > let _: (Int) -> () = {} > let _: (Int, Int) -> Int = { 5 } > let _: (Int, Int) -> Int = { $0 } > let _: (Int, Int) -> Int = { $1 }
+1 -- -Dave _______________________________________________ swift-evolution mailing list [email protected] https://lists.swift.org/mailman/listinfo/swift-evolution
