State: You're Doing It Wrong - Alternative Concurrency Paradigms For The JVM

"State: You're Doing It Wrong - Alternative Concurrency Paradigms For The JVM"

"What is an Identity?
A stable logical Identity associated with a series of different Values over time."

"What is State?
The Value an entity with a specific Identity has at a particular point in time."

"Haw do we know if something has State?
If a function is invoked with the same arguments at two different points in time and returns different values ... than it has State."

P.S. More on State (Clojure)

JAOO: The Clojure Concurrency Story

Слайды с презентации Rich Hickey "The Clojure Concurrency Story" на JAOO Conference:
http://jaoo.dk/aarhus-2009/file?path=/jaoo-aarhus-2009/slides/RichHickey_TheClojureConcurrencyStory.pdf

Abstract:

All functional programming languages emphasize working with immutable data as much as possible. How can that be efficient, and what benefits does it bring? And what happens when you need state, to manage changing values over time? One method is to use mutable references with concurrency semantics, such as transactions, coupled with persistent data structures. This combination makes for easy, lock-free designs, well within the comfort zone of those used to imperative programming.

This talk discusses how immutability, state and identity are handled in the Clojure language. You'll learn details about Clojure's managed references, agents and STM.

Target audience: Developers interested in alternative approaches to concurrency.