The Clojure model of state and identity

Clojure has very strong opinions about concurrency, in order to take it in a simpler way it redefines what state and identity mean. Let's explore the meaning of this concepts in Clojure.

When talking about state in Java, you probably think about the values of the attributes of your Java classes. The state in Clojure is similar to Java, it refers to the values of objects but there are very important differences that allow simpler concurrency.

In Clojure, identity is an entity that might have different values over time. Consider the following examples:

• I have an identity; I will be and continue being this particular individual, my opinions, ideas, and appearance might change over time but I am the same individual with the same identity.

• You have a bank account; it has a particular number and is run by a particular bank. The amount of money you have in it changes over time, but it is the same bank account.

• Consider a ticker symbol (such as GOOG), it identifies...