Getting Clojure

In the Wild

Maps are the Swiss Army knives of Clojure programming: any time you need to bundle together some related data items into a unified whole, one of your first thoughts should be, Hey, I’ll use a map. You can see this thinking at work in the clojure.java.jdbc library, which provides an easy-to-use Clojure interface to a wide variety of relational databases. The functions supplied by clojure.java.jdbc need several pieces of configuration information to find your database, which you supply with a map:

(require 'clojure.java.jdbc)

(def db {:dbtype "derby" :dbname "books"})

(clojure.java.jdbc/query db ["select * from books"])

In the example, the map bound to db contains the database connection information. Don’t worry about ...