The documentation for Kotlin is now located on the new site. This page is kept for historical reasons

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The documentation for Kotlin is now located on the new site. This page is kept for historical reasons

Note: If you've come to this page from an external link, please start reading at the Welcome page, not this one.

Project Kotlin was born in Saint Petersburg, Russia, where one of the main JetBrains' development offices is located. Kotlin is the name of an island situated nearby Saint Petersburg, in the Gulf of Finland, with a beautiful town of Kronstadt build upon the island. The current logo was inspired by the probably imagined connection of the word "Kotlin" with the word "Kettle", which was originally mentioned in the 1911 edition of Encyclopedia Britannica.

Disclaimer 1: We believe that no coffee or other exotic cultures are grown in Kotlin in any noticeable quantities.

Disclaimer 2: Despite the fact that Kotlin Class Destroyers were named after the same island, our language is not intended for class destruction by any means.

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  1. Anonymous

    I'd change the colors, though. Looks like a Google language to me :)

    1. Anonymous

      Totally agree.

  2. Anonymous

    Hm, the name "Kotlin" sounds very unpleasant to me.

    But I like the language the more... can't wait to write some real code in it, so please hurry on :-)


    1. Anonymous

      In German, Kot = Shit, and Kutteln (which sounds similar) is tripe (this is how it looks: Trippa.jpg)

  3. Anonymous

    You shoud be thinking... One more language !?!?!

    But It's always a good idea!!!

    I agree....

  4. Anonymous

    Hurry up guys!  I want to play with it!! :)  Ignore all the Scala dudes complaining how it's like Scala.  If it was like Scala, only wankers would be interested.

  5. It may be been said elsewhere but deserves repeating.

    Thank you for the best practices, Effective Java and motivation references.  It is a delight to see the thinking behind your designs.  I expect Kotlin to be used as a CS case study for language design; your reasoning is explicitly stated.

    1. Thanks for your kind words.

  6. Anonymous

    Is there any news about this project? I hope I can try it as soon as possible, I can't wait

    1. It's not too long to wait. We plan a public Beta by the end of the year.

      Meanwhile, you can watch our progress in the blog and twitter.

      1. Anonymous

        Can't await the end of this year! The language looks pretty balanced to me. Godspeed!

        1. Thanks for your kind words

  7. Anonymous

    Also can't wait for it to come out. Looks nice!

  8. Anonymous

    Kotlin is also best Polish ketchup made in the city with the same name.

  9. Anonymous

    Can you compare it also with gosu(http://gosu-lang.org/), phantom (http://fantom.org/) and grovy++ (http://code.google.com/p/groovypptest/)

    1. I guess, the community will provide a detailed comparison at some point. Some quick highlights:

      How Kotlin differs from Gosu:

      • one can compile a program and distribute binaries (Gosu only compiles on-the-fly).


      • Kotlin has user-defined generic types and functions

      Groovy++ is a very nice demonstration of how much you can do if you want to turn a dynamic language into a static one. Kotlin is inherently statically typed.

  10. Anonymous

    Thanks guys, it's a great puzzle gathered from Scala, Groovy, C# and Java! I think it is yet not late to do a little research regarding the meaning of word "Kotlin" in other languages and the coloring of the logo which really resembles the ones from google..

    Wish your language become popular! 

    1. When Kotlin .NET backend will be implemented? How can I speed up this process? :)

      1. We didn't start working on this yet. You can speed it up by contributing the implementation (smile)

        1. I'm ready to try, what should I do first? Please feel free to contact me by e-mail in Russian.

          1. You can have a look at how the Java and JS back-ends work, and implement your own back-end for .NET.
            I think, the first step would be to find a Java library that would allow you to emit IL and try to use it independently from Kotlin. When that works, you can start to translate simple Kotlin constructs taking inspiration from our existing back-ends.

            Please feel free to ask questions in forums or contact me personally by email: andrey.breslav jetbrains com

  11. sounds a bit like Dart... do you think you can stand against Google's new&mighty VM language?

    1. Do you think Google's yet another VM language can stand against new&mighty initiative from Jetbrains?

    2. I think we fit very easily into the same world (smile)

      1. True. From my point of view, Kotlin is especially important to JetBrains as that's the way to bring IntelliJ (with it's huge JVM/Java code base) to the browser.</speculation>

        I'll write some additional server-side parts of my GWT app in Kotlin as soon as its production-ready. I've done the same thing with  Scala two years ago and it was a mess: Scala doesn't play nicely with Java as soon as Java's language constructs become complex. I've read that you've addressed this problem in Kotlin as "(strong?) compatibility".

  12. Is there some extension functions for encapsulate List<T> as Iterable (for example, asIterable()) ? 

    and is there extension functions for Iterable same as in C# for IEnumerable (class Enumerable)?

      1. where can I read something about it?

        1. Currently it's only in the source code of the standard library. It is available here: https://github.com/JetBrains/kotlin/tree/master/libraries/stdlib