Perception and action are radically different. Clojure's time model makes it easy to build systems that model the real-world differences between perception and action. In this talk, you will learn how to think using 

• values: immutable data items, both atomic and composite

• identities: entities that take a series of causally-related values over time

• time: a before/after ordering of perceptions and actions

• references: point-in-time values of an identity

Getting time right is essential for modeling concurrency effectively, but its importance does not stop there. Without a good model of time, it is difficult to deal sensibly with currency and history, much less concurrency and parallelism.

The ideas in this talk will help you create better programs that more faithfully model the world, even if you write linear programs that hope to never see a second thread.