Edit: The post previsouly said yielding accessors were available only in nightly toolchains, but _read and _modify are also available in release Swift builds; they’re just _ prefixed to signify they are work-in-progress. It seems that Swift 5.6 is shaping up to a great iteration of the language and will bring a round improvements to performance-critical Swift code. I was reading through a pitch by Joe Groff on some improvements to ARC and ownership the other day when I noticed that he mentions that accessor coroutines are available in Swift trunk. …