Book Image

The Clojure Workshop

By : Joseph Fahey, Thomas Haratyk, Scott McCaughie, Yehonathan Sharvit, Konrad Szydlo
Book Image

The Clojure Workshop

By: Joseph Fahey, Thomas Haratyk, Scott McCaughie, Yehonathan Sharvit, Konrad Szydlo

Overview of this book

The Clojure Workshop is a step-by-step guide to Clojure and ClojureScript, designed to quickly get you up and running as a confident, knowledgeable developer. Because of the functional nature of the language, Clojure programming is quite different to what many developers will have experienced. As hosted languages, Clojure and ClojureScript can also be daunting for newcomers because of complexities in the tooling and the challenge of interacting with the host platforms. To help you overcome these barriers, this book adopts a practical approach. Every chapter is centered around building something. As you progress through the book, you will progressively develop the 'muscle memory' that will make you a productive Clojure programmer, and help you see the world through the concepts of functional programming. You will also gain familiarity with common idioms and patterns, as well as exposure to some of the most widely used libraries. Unlike many Clojure books, this Workshop will include significant coverage of both Clojure and ClojureScript. This makes it useful no matter your goal or preferred platform, and provides a fresh perspective on the hosted nature of the language. By the end of this book, you'll have the knowledge, skills and confidence to creatively tackle your own ambitious projects with Clojure and ClojureScript.
Table of Contents (17 chapters)
Free Chapter
2
2. Data Types and Immutability

Truthiness, nil, and equality

Up until now, we have been using conditional expressions intuitively, possibly on the basis of how they usually work with other programming languages. In this final section, we will review and explain Boolean expressions and the related comparison functions in detail, starting with nil and truthiness in Clojure.

nil is a value that represents the absence of value. It is also often called NULL in other programming languages. Representing the absence of value is useful because it means that something is missing.

In Clojure, nil is "falsey," which means that nil behaves like false when evaluated in a Boolean expression.

false and nil are the only values that are treated as falsey in Clojure; everything else is truthy. This simple rule is a blessing (especially if you are coming from a language such as JavaScript) and makes our code more readable and less error-prone. Perhaps it's just that Clojure was not out yet when Oscar Wilde wrote...