Quick summary of Kotlin and why you'd want to use it in Android:<p><pre><code> Lambdas
Fairly lightweight, probably looking at 10% overhead only
Can ducktype existing classes. eg add "hello".reverse()
IDE support in Jetbrains (but not in eclipse)
Can turn 'try..finally' into library methods
Full interop with java files in same project
val/var types help to reduce side effects</code></pre>