[mike_hearn]

I like Kotlin too but in fairness this is a Ceylon thread ;)

From what I can see, Ceylon has a blend of strengths that should make it appeal to a certain segment of the market. On one hand, it's a fresh start and has a lot of the cleanness and terseness that I like from Kotlin. On the other, Gavin is clearly very much into type systems and type theory, and Ceylon has a more complex/powerful type system than Kotlin does.

I'll admit that I'm not totally sure whether the additional complexity is worth it, but I'm very open to being persuaded.

So it seems to me like Ceylon should appeal to people who currently like Scala or Haskell and push the type systems to the limit, but really want something without historical baggage like XML literals and other oddities. And I'm sure there are plenty of programmers like that.

The real question will be interop costs. Kotlin doesn't have any and that's the main reason people can consider it in existing projects, or introduction inside large corporations. Ceylon takes a more Scala-like approach where it has its own standard library, its own collections, etc.

[on_and_off]

not having interop costs also makes Kotlin much more realistically useable for Android apps, which could really help bootstrap its adoption.

Android could use a better language than Java 7 (or even 8) and Kotlin seems to be the only one that can easily replace it.

[gavinking]

Well the thing is that Ceylon offers fantastically smooth interop with both Java and JavaScript. That's one of it's main selling features for most people.

[mike_hearn]

Right, but by "interop" I didn't just mean the ability to call into Java code and vice-versa, although I admit that's the traditional definition. Scala can do that too.

What I meant is, Kotlin raised the bar in the interop department to new heights: it uses the same collection types, so there's no conversion between Java and some other SDK, but still manages to enhance them via compiler magic and extensions. It has an auto-converter tool so nobody has to waste time rewriting code that already works in order to use the new features. It can use annotation processors, etc.

Of course it also pays a fairly steep price to get that.

[justthistime_]

> but still manages to enhance them via compiler magic and extensions

The thing is that Scala tried to do that for years, and after years of battling subtle, leaky abstractions, they picked a different design.

It feels like Kotlin designers are completely unaware of what other languages tried and keep repeating all the mistakes ...

[mike_hearn]

Hardly. The Kotlin designers specifically call out Scala's mistakes when discussing why they do things differently.

In my experience it works well. I've yet to encounter anything surprising or leaky. Actually the abstractions it provides are fairly thin: you can normally look at Kotlin code and understand quickly what it compiles down to.

It may be that in the end, Kotlin succeeds where Scala struggled, simply because the Kotlin designers do a better job.

[justthistime_]

Well, I don't think what you say is based on reality if you look at all the broken, half-designed stuff they are trying to ship. (Not understanding (yet) why some design decisions are bad, doesn't mean they aren't bad.)

It feels like they are digging through Scala's graveyard of discarded ideas without even realizing it. Most of what they try to do differently has already been considered in the past and has been rejected by the Scala developers for good reasons – years ago.

Kotlin's struggles are a good example that knowing how to build IDE support for existing languages doesn't give you the skills to design a programming language from scratch.

    The Kotlin designers specifically call out Scala's
    mistakes when discussing why they do things differently.

Yes, I have to give them that. They (and their "fans") excel at PR, marketing and FUD.

[modersky]

Different languages have different design tradeoffs. I had many profitable exchanges with Andrey Breslav and other Kotlin designers. We can have a technical discussion about the design choices without getting into a fight about who is more competent.

[udalov]

Could you please give a few examples of "all the broken, half-designed stuff they are trying to ship"?