"Mutable stateful objects are the new spaghetti code" --Rich Hickey

In Java most classes are mutable and that's the default, so that’s the way that most Java developers write code. In this talk you’ll see why mutable code fails: though easy and fast in the short term, you end up with a complex mess that's hard to understand, test or reason about, and is a concurrency nightmare to boot. Finally, we'll challenge the prevailing paradigm, exploring how simple immutable objects excel in these same cases.