#Swift uses something like this:

“Simple Fast Value Semantics”, Tibor ‘zupa’ Halter, #Boomla (https://boomla.com/docs/simple-fast-value-semantics).

“isKnownUniquelyReferenced(_:)” (https://developer.apple.com/documentation/swift/isknownuniquelyreferenced(_:)-5kvtu).

Via Lobsters: https://lobste.rs/s/xo7a4v/simple_fast_value_semantics

On HN: https://news.ycombinator.com/item?id=41138550

#PLDI #CopyOnWrite