Not sure what's up with it now, but Etoile seemed to have a very interesting implementation of an Obj-C runtime: http://etoileos.com/etoile/features/runtime/ ht

Not sure what's up with it now, but Etoile seemed to have a very interesting implementation of an Obj-C runtime: http://etoileos.com/etoile/features/runtime/ http://etoileos.com/etoile/features/runtime/ I would have hoped to see something with a more dynamic runtime than we ended up with with Swift. That said, while it feels like a big win to dynamically recompile, say, calls to retain/release into simple atomic increments/decrements, or dynamic calls into direct calls, in practice the wins never seem to appear. Is it just because no-one tried hard enough? :-)