turing complete with a stack of 0xdeadbeef
UIKit provides two diffable data source APIs, one for collections and one for tables. Recently, while working on ReactiveCollectionKit, I noticed that the APIs were updated for Swift Concurrency in the iOS 18 SDK, but the annotations were inconsistent with the documentation.
If you have attempted to adopt Swift Concurrency in your codebase, you have certainly needed to address dozens — likely, hundreds — of warnings and errors. Sometimes the issues can be resolved by addressing them directly. That is, your code was incorrect and you simply have to fix it to make it correct. In other scenarios, the resolution is not so straightforward. In particular, it is difficult to satisfy the compiler when working with APIs that you do not own that have not been updated for concurrency. Or, you may have found yourself in a situation where you know your code is correct, but the compiler is unable to verify its correctness — either because of a few remaining bugs in Swift Concurrency, or because you are using @preconcurrency APIs.
While debugging some code the other day, I wanted to verify the behavior of global variables and static members in Swift. I vaguely remembered from the early days of Swift, that static let members and global constants were atomic and computed lazily — one of the many improvements over Objective-C.