The name for the variable is kind of weird, it feels a bit like Java (having 25 years of history to account for). I wonder what the Kotlin for JS will be.
Kotlin is more like a mixture of Typescript and/or Reason (or whatever the name is now)
Groovy was that flash-in-the pan idea that had some really cool ideas.
But then again, I'm not sure if it really inspired any real language changes to Java like Kotlin has. CoffeeScript did a TON of inspiration for ES6... so heck, maybe Kotlin IS the CoffeeScript
I hope Kotlin survives though.