10 years on, what would you change about Swift?

[johnno1962 (John Holdsworth)]

@tera

Let me run this idea by you of making ABI compatibility story differently:

I'd wanted this to be possible but when Apple starts using in Swift in their frameworks it breaks:

@johnno1962

I wonder though would it be possible to introduce the concept of an “ABI stability window” where these libraries are versioned and Xcode would adjust the RPATH built into the application so apps built with different versions of Swift would use different versions of the shared Swift libraries. In this model the ABI would not be fixed forever (which is a very long time) but for the duration of the window.

/System
	Library
		Swift
			4_2
				libSwiftCore.dylib
				HealthKit.framework
			5_0
				libSwiftCore.dylib
				HealthKit.framework

The best summary was @jrose's Swift was always going to be part of the OS // -dealloc I always wondered if there could be a middle road with layers of ABI between these absolutes (where multiple version of SwiftUI could be supported for example) but it would need to be pretty well thought out. The advantages are twofold, apps don't break or change their behaviour when users upgrade the OS and the library designers get to evolve their ABI's (APIs - ABI is something lower level.) more freely.