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

Introduction

This chapter is about using Clojure's reduce function and about reducing in general. By that, we mean starting with a sequence and boiling it down to a single thing. ("Reducing" is also cooking term, after all.) map and filter were about taking the sequence you have and turning it into the sequence you want: sequence in, sequence out. But that's not always what we want. Even simple operations on a sequence, such as calculating an average, a sum, or a maximum, cannot be directly calculated this way. That's where reduce, as well as a wider family of functions and patterns, comes in: sequence in, something else out. It's "something else" because the result might be a number, a string, a map, or even another sequence.

In the previous chapter, we saw that functions such as map and filter only look at one element at a time: how should we transform this item? Should we discard this item, or keep it? This is a powerful approach because...