None of those things compile to Objective-C. They each provide a runtime for C#, Javascript and Ruby respectively with bindings to the underlying Objective-C a

None of those things compile to Objective-C. They each provide a runtime for C#, Javascript and Ruby respectively with bindings to the underlying Objective-C apis. And they each do it in a different way, with different levels of layers between the normal Cocoa APIs. What 'language infrastructure' are you talking about?