the main difference between java and pg vs closure and datomic (not: diatomic) is "immutability", which implies a different way of thinking about multithreading

the main difference between java and pg vs closure and datomic (not: diatomic) is "immutability", which implies a different way of thinking about multithreading and multiprocessing and transactions. instead of locking and mutexes and semaphores you think in terms of branching and merging, much like git or similar VCS systems. what is "hipster" about that?