Clojure Cookbook

Chapter 1. Primitive Data

1.0. Introduction

Clojure is a fantastic language for tackling hard problems. Its simple tools let us software developers build up layer upon layer of abstractions until we’ve tackled some of the world’s most difficult problems with ease. Like chemistry, every great Clojure program boils down to simple atoms—these are our primitives.

Standing on the shoulders of the Java giants from days of yore, Clojure leverages a fantastic array of battle-hardened types present in the Java Virtual Machine (JVM):^[1] strings, numeric types, dates, Universally Unique Identifiers (UUIDs)—you name it, Clojure has it all. This chapter dives into the primitives of Clojure and how to accomplish common tasks.

Strings

Almost every programming language knows how to work with and deal in strings. Clojure is no exception, and despite a few differences, Clojure provides the same general capabilities as most other languages. Here are a few key differences we think you should know about.

First, Clojure strings are backed by Java’s UTF-16 strings. You don’t need to add comments to files to indicate string encoding or worry about losing characters in translation. Your Clojure programs are ready to communicate in the world beyond A–Z.

Second, unlike languages like Perl or Ruby that have extensive string libraries, Clojure has a rather Spartan built-in string manipulation library. This may seem odd at first, but Clojure prefers simple and composable tools; all of the plethora of collection-modifying ...