JVM rookie Kotlin gets first milestone release

The latest language to join the list of those executable on the JVM, Kotlin has had a whirlwind 2012 so far. January saw it unveiled to the public with a fully-testable preview, and the following month it was open sourced for onlookers. Now we get to see the first big leap towards a full version of JetBrains’ statically-typed language with Milestone 1 available to view.

Aimed to fit seamlessly alongside IntelliJ, the following goals were in mind for Kotlin:

• to compile to the JVM/JavaScript,
• that Kotlin compiles at least as fast as Java,
• that Kotlin is safer than Java, i.e. statically check for common pitfalls such as null pointer dereference,
• to make it more concise than Java by supporting variable type inference, higher-order functions (closures), extension functions, mixins and first-class delegation, etc;
• and by keeping the useful level of expressiveness and make it way simpler than the most mature competitor – Scala.

As you can see, some lofty aspirations but with a good reason – JetBrains have done a fine job with Milestone 1. Kotlin comes in the form of a standalone compiler (download here) and a plugin for IntelliJ IDEA within the official repository.

Some of the stuff you can do to Java API with the Standard Library is impressive. For example, enable bulk data processing with map()/filter()/etc available on collections:

val minors = users.filter { it.age < 21 }

As well as fully fleshing out their documentation and homepage with bucketloads of info about Kotlin, there’s full GitHub support, the possibility of annotations and multi-line string templates, code completion for extension functions, local functions and a byte code viewer.

It’s an excellent start and we can only expect the JetBrains team to add in futher tidbits to make Kotlin a language to keep an eye on.

The future’s bright for this JVM rookie, especially coming from the JetBrains team – congratulations on seeing your year’s work come to fruition guys!