Book Image

Clojure Programming Cookbook

Book Image

Clojure Programming Cookbook

Overview of this book

When it comes to learning and using a new language you need an effective guide to be by your side when things get rough. For Clojure developers, these recipes have everything you need to take on everything this language offers. This book is divided into three high impact sections. The first section gives you an introduction to live programming and best practices. We show you how to interact with your connections by manipulating, transforming, and merging collections. You’ll learn how to work with macros, protocols, multi-methods, and transducers. We’ll also teach you how to work with languages such as Java, and Scala. The next section deals with intermediate-level content and enhances your Clojure skills, here we’ll teach you concurrency programming with Clojure for high performance. We will provide you with advanced best practices, tips on Clojure programming, and show you how to work with Clojure while developing applications. In the final section you will learn how to test, deploy and analyze websocket behavior when your app is deployed in the cloud. Finally, we will take you through DevOps. Developing with Clojure has never been easier with these recipes by your side!
Table of Contents (16 chapters)
Clojure Programming Cookbook
About the Authors
About the Reviewer

Merging and splitting collections

Sometimes, you'd like to merge multiple collections into a single collection or split a single collection into multiple collections. Let's have a look these cases.

Getting ready

You only need REPL, described in the Repl up! recipe in Chapter 1, Live Programming with Clojure, and no additional libraries. Start REPL, and you can review the sample code in this recipe.

How to do it...

Let's see how to merge and split collections.

Using merge and merge-with for merging

The merge function merges multiple maps into a single map. If there are the same keys among maps in arguments, latter entries override former entries:

(merge {:a 1 :b 2 :c 3} {:c 4 :d 5 :e 6}) 
;;=> {:a 1, :b 2, :c 4, :d 5, :e 6} 
(merge {:a 1 :b 2 :c 3} {:c 4 :d 5 :e 6} {:c 7 :f 4 :g 6}) 
;;=> {:a 1, :b 2, :c 7, :d 5, :e 6, :f 4, :g 6} 

The merge-with function is more amazing:

(def nicos-fruits 
  {:apple 10 :melon 15 :orange 2 :pear 12} 
;;=> #'collection...