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Comment by adamnemecek | Hacker News Reader

I agree 100%. Kotlin compiles to JVM, JS and very soon also to native via LLVM. That means you can ship a web app (both backend & frontend) and mobile clients (for android and soon iOS) in one language. This is unprecedented.

For JS, you can use all you favorite front-end frameworks like react (here's an example by JetBrains themselves https://github.com/Kotlin/kotlin-fullstack-sample) or cycle. And you can import typescript definitions.

Also first class IDE integration.

So yeah, bright future is an understatement.

I guess clojure/clojurescript and scala.js are somewhat similar however I feel like Kotlin has an insane amount of momentum behind it right now.

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Kotlin is the first language I've gotten excited about in a long time. It's close enough to Java that I can get my engineers up to speed in a few hours, but it removed a lot of the bloat and tedium.

The JNV / JS / Native targets are also really promising, though I haven't played around with them much. The JS and Native runtimes are a bit limited since they don't include the Java standard library, from what I can tell.

> The JS and Native runtimes are a bit limited since they don't include the Java standard library, from what I can tell.

I think that they ship with the Kotlin standard library which is close enough.

Cross Compilation isnt unprecedented various lisps have been doing it for decades. There are many lisp solutions thats do it already. Including Clojure which ships to Backend Frontend and Mobile Apps. Nothing new here.

Not talking about cross-compilation, I'm talking about having a industry-grade, production ready language that I can ship stuff in like yesterday.

> various lisps have been doing it for decades

There's an insanely long road from having a prototype of a language to having a production ready thing. There isn't a lisp where I could achieve the same experience.

>I'm talking about having a industry-grade, production ready language.

It isnt a mature enough language to be trusted so soon, no body has a sufficient enough industry grade experience with it. Especially with large code bases.

> It isnt a mature enough language to be trusted so soon,

I mean, Google adopted it as a first class citizen language on android which counts for something.

> no body has a sufficient enough industry grade experience with it. Especially with large code bases.

There aren't really any "new" features in Kotlin, as in features you haven't seen before. If you've been programming Java and know some Haskell/Ocaml or idk what else, you are good to go.

> I mean, Google adopted it as a first class citizen language on android which counts for something.

Something but not much. It works on JVM, talk to all Java libs and tooling is taken care by Intellij. It is low or little effort from Google to support. Unlike other language fans who clamor for Android support from Google, here hard work is done by someone else. So Google support looks most like a co-branding deal.

Not what we are arguing about. We are arguing about if Kotlin is mature or not, googles invovelement is irrelevant.

> This is unprecedented.

C/C++ can do that if you accept Emscripten.

Java can do that if you accept GWT.

Haxe can do it as well.

Though I think what really sets it apart (on the web side) is that it interops pretty well with other js libs.

I think what sets it apart is the interopability with it's current targets. Really slick

Edit:fixed typo

> C/C++ can do that if you accept Emscripten.

Yeah, pls no.

> Java can do that if you accept GWT.

Yeah, I don't. Google abandoned it, you should too.

Still, they count as 'precedents'.

Precedents are nice and all but I want something I can ship stuff in.

Google still ships stuff using GWT - they just talk about it much.

They maintain legacy stuff written in GWT, I dont know any new projects that use it.

Vaadin is built on GWT and seems quite alive. https://vaadin.com/

Vaadin is doa. It’s not a spa which means it will be dead in idk three years. People love that interactivity.

Nim doesn't have a JVM backend, but it does C, C++, Objective-C, JavaScript, LLVM (not yet ready for prime time, but almost there), iOS, Android, and more.

Lisps have been doing this since forever (including the now defunct LinJ for Java which compiled into code that was very often mistaken for hand-written Java).

Hell, Emscripten takes everything LLVMable and gives it that ability.

> This is unprecedented.

Only for sufficiently narrow "this".

> This is unprecedented.

Don't get me wrong, I like Kotlin, but Ceylon did the multi platform thing much better.

They have real platform modules, built into the language (not just a build tool trick), and a language specification that was written from the start with multiple platforms in mind.

But it never took off (yet), and Kotlin's support is good enough, so it will have to do I guess :).

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You could also do this with JavaScript correct? Node.js back end with whatever front end framework and then use something like react native for mobile?

That's not quite there though - with React Native, your still running the js engine to run the JavaScript (but your at least using native widgets).

With Kotlin you'll be running compiled code. If you wanted to right now though, you could (should be able to?) use Kotlin to build a React Native app with it's just target.

I was looking into this yesterday. Apparently while there's support for transpiling Kotlin -> JS, more work would be needed to support transpiling for react native[1]. Not sure why.

[1] https://blog.jetbrains.com/kotlin/2017/04/use-kotlin-with-np...

But then you'd be writing JavaScript and who wants that. TypeScript is maybe ok-ish but TS is just putting a lipstick on a pig. Like, ignoring other issues, JVM at least has decent concurrency and with quasar, you get processes similar to erlang.

What about the other side of that coin. Does a small amount of idiomatic Kotlin compile down to a small amount of JS, or a large amount (in bytes, after gzip)?

I don't have extensive experience with it but it's not too bad compared with other JS transpilers.

Since the kotlin runtime is rather small, you still have to deal with platform differences.

I like kotlin for several reasons but this one isn't on the top of my list. If you like cross-platform development, you might want to check out haxe.

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