Volatiles and vswap! were added in 1.7 as performant mechanisms to achieve uncoordinated mutation to the language.
given the fact that their addition was a performance-centric one, vswap! was implemented as a macro rather than a normal function to avoid runtime dereference of the function var and the optional apply overhead in case of multiple args.
-is not necessary
-breaks the api parallelism between volatile/atom swap!/vswap! reset!/vreset!
-makes impossible certain use cases (vswaps! in update-in forms)
-is potentially confusing given that swap! is a function
Infact the macro can be replaced with a function with :inline metadata.
This is a strictly additive change that will make so that for all the current valid usages of vswap! nothing will change, it will still be macroexpanded by the inliner and additionally since it is now a function it can be used in HOF contexts where it's not unusual to see swap! used.