Let me first say I love Java. There is a reason it’s the most popular programming language in the world. For me personally, I made a career out of building systems in Java, and I even teach a course in Java. But when it comes to Big Data, Java simply doesn’t cut it. Everybody knows functional languages have enjoyed a renaissance as Big Data has become a thing. And for good reason: immutable (or mostly immutable) state, lazy evaluation, the natural fit with recursion, and so on.