[simon_void]

not sure what "(non)-isomorphic" but Kotlin code is interoperable with Java code in both directions. You can easily call Java-code from Kotlin (but I guess that's the easy direction) but you can also call Kotlin code from Java. There exist specific annotations to control how Kotlin code will be converted to bytecode and therefore be invoked from Java, e.g. a function in a Kotlin companion object would normally concerted into a function of a Singleton property called INSTANCE on the base class, but if you annotate it with @JvmStatic it will become a static method of that class in bytecode instead. This means you can write a Kotlin lib that feels very normal to call from Java. here's the relevant part of the documentation: https://kotlinlang.org/docs/java-to-kotlin-interop.html So yes, Kotlin is considered to be a successor language, not just another language (also) compiling to the JVM.

[treyd]

An isomorphism is a structure preserving 1:1 map between two sets or some other pair of structures. While Java and Kotlin are interoperable (because they both target the JVM), they are not isomorphic for precisely the reasons you described. If it was, then you could do round trip machine translation on the syntax in either direction and have a result that's identical to the original. You can't do that because Kotlin extends Java in nontrivial semantic ways (for a concrete example, see Nothing in the article you linked).

Cpp2 isn't trying to be a successor language to C++, the article states that it's trying to present an identical feature set in a new skin where the best practices of modern C++ are more ergonomic without introducing any new functionality.

[tialaramex]

> Cpp2 isn't trying to be a successor language to C++

Herb is trying to sell it as not a successor because for now that suits him better.

Because C++ is a general purpose language Herb can deliver a "not a new feature" that is so elaborate in practice you would never write the equivalent C++ by hand, but Herb can insist that since technically it can still be transpiled to C++ it's not a different language... right up until that ceases to suit his agenda.

Under this model WUFFS (a higher performance yet entirely safe language for writing stuff like codecs and compression algorithms) doesn't "introduce any new functionality" compared to C, since the present WUFFS-the-language is transpiled into C. But I think C programmers would be astonished to hear that C is now apparently higher performance than C and is able to guarantee it's entirely safe...

[treyd]

The linked article explicitly states

> What it isn't. Cpp2 is not a successor or alternate language [...]

[tialaramex]

That's correct, Herb Sutter does indeed claim that his C++ Successor Language isn't a C++ Successor Language, as I stated.

[pjmlp]

Mostly because it would look odd if the WG21 chair, would also sell his language as a C++ successor language, lets not fool ourselves it is something else.

[pjmlp]

Try to call Kotlin co-routines directly from Java to see how it goes.

Or call Java features from Kotlin, that aren't available on Android.