Getting Clojure

A Place for Your Vars

In the last chapter we saw how def creates vars—vars that represent the binding between a symbol and a value. What we skipped over in that chapter is how vars are organized. But really it’s very simple. As illustrated in the figure, vars live in namespaces.

Conceptually, a Clojure namespace is just a big lookup table of vars, indexed by their symbols. And since you can have as many namespaces in your program as you want, each namespace itself has a unique name. At any given moment there is one special namespace, called the current namespace. So if you do this:

namespace/examples.clj

(def discount-rate 0.15)

it’s the current ...