> Sure, it's possible that there are some differences in how we both do interop

There are no "some differences", but a radically different philosophy which is at the very core of the language's design. A Kotlin list is a Java list and vice-versa; a Kotlin map is a Java map and vice-versa; a Kotlin set is a Java set and vice-versa. The same, BTW, is true for Clojure, but unlike Clojure, Kotlin doesn't just keep the interfaces, but also the implementations. Kotlin hardly even has a standard library. The Java standard libraries are Kotlin's standard libraries (modulo some extension methods). Ceylon has its own standard libraries, and, in general, Java libraries are not idiomatic Ceylon libraries. That Ceylon even has CeylonList/JavaList types shows how the two approaches are worlds apart. Comparing it to Kotlin in that regard is ridiculous, and I don't even know why you'd try. It is one of Ceylon's strengths that it has its own library, and one of Kotlin's that it doesn't. Each appeals to different needs, and I don't see why you feel you should blur the differences.

> When you do try and find interop things that we should improve

It's not about that. You may think that Ceylon's Java interop is great. It may be just the right amount of interoperability that you want. But claiming it is anywhere near Kotlin's is just preposterous. I didn't say that Ceylon's Java interop is bad, but it's just not even in the same ballpark as Koltin's. But that's OK, because the two languages have different philosophies.

> Meanwhile, please stop with the FUD.

Please stop calling it FUD. I have never, ever said people shouldn't use Ceylon, that it's a bad language or even that Kotlin is better. I have emphasized the big difference in design goals between the two languages that makes them very different in practice: Ceylon has an advanced, very elegant, beautiful type system, while Kotlin has many thousands of libraries. Where is the FUD?

OTOH, instead of calling it FUD, and since this is a Ceylon thread, I would very much like to hear a justification for Ceylon's design; not the choices of the particular language features -- I will readily admit that Ceylon is the best language ever devised by man -- but why being better at the language/typesystem level, without offering a new paradigm warrants switching a language in the first place. After all, it doesn't offer anything radical when it comes to concurrency (like Clojure or Erlang or Go) or functional purity/equational reasoning (like Haskell). It's just cleaner and more elegant than Java or Scala. OCaml is another such beautiful, well-designed language, but, perhaps sadly, it has hardly seen any adoption. Why do you believe that is enough to get people to switch to a new language? For example, I know that Joe Armstrong thought a lot about the problem of fault-tolerant systems, and he came up with the idea of isolating failure; Rich Hickey thought a lot about state and identity and came up with Clojure's data structures and controlled mutation. Their reasoning is fascinating. What is that behind Ceylon's (I can tell you the reasoning behind Kotlin)? Did you reach the conclusion that a major obstacle to building modern software at this point in time is deficiencies in the type system? I'm not mocking, and I'm not saying it isn't, but unlike in Clojure's, Erlang's, Rust's and Kotlin's case (or Haskell or Scala), I've just never seen the Ceylon philosophy explained.

I've read Ceylon's guiding principles, but they haven't answered the question. If simply doing the same thing better justifies starting over, then supposing Ceylon takes off, in a few years Ceylon, too, will accumulate cruft, and its design mistakes (in the language or libraries) will become apparent. What will Ceylon advocate then? Backwards compatibility or breaking changes (or maybe a new language altogether)? And if the idea is to start over every 20 years -- I can see the merit in that argument -- why not a whole new paradigm? Is everything OK except mistakes in library design and the type system?

You don't have to answer, and you can either address or ignore my views -- but please don't call them FUD.