Clojure Programming Cookbook

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!

Clojure Programming Cookbook

Credits

About the Authors

About the Reviewer

www.PacktPub.com

Preface

Free Chapter

Live Programming with Clojure

Introduction

REPL up!

Working with primitive data types

Using bindings of vars, conditions, loops, and error handling

Using and defining functions

Using third-party libraries

Using namespaces

What's next?

Interacting with Collections

Introduction

Clojure collections and their basic functions

Accessing and updating elements from collections

Filtering elements from collections

Transforming and sorting collections

Merging and splitting collections

How to become lazy

Clojure Next

Introduction

Using destructuring techniques

Using functional programming style

Using threading macros

Defining simple macros

Defining more advanced macros

Using protocols

Defining multimethods

Transducers for dummies

Logic programming in Clojure

File Access and the Network

Introduction

Manipulating files and directories

Manipulating various formats of files - XML, JSON, YAML, and EDN

Making use of Clojure HTTP client

Using queues and topics in the RabbitMQ

Using Kafka

Using MQTT

Streaming access to provide high performance

Using Apache Camel to connect everything

Working with Other Languages

Introduction

Calling Java methods and accessing Java objects from Clojure

Extending Java superclasses and implementing Java interfaces

Calling Clojure from Java

Calling Scala from Clojure

ClojureCLR

ClojureScript

Concurrency and Parallelism

Introduction

Solving concurrent problems using Clojure

Distributed actor-based dev with Akka

Using Spyglass and Couchbase to share state between JVMs

Reactive programming with meltdown

Bridging core.async

On Quasar/Pulsar

Advanced Tips

Introduction

Hacking the Clojure code

Using Reader Conditionals, compile to Clojure, and ClojureScript

Real-time shared development with an REPL

Declarative data descriptions and validations with plumatic/schema

Web Applications

Introduction

Clojure with Vaadin - easy web widgets

Quickly create a REST API with Liberator

Working with Immutant - reusing infrastructure

Developing with om.next, the next-generation ClojureScript library

Testing

Introduction

Behavior-driven development

Testing with random inputs and pattern-based testing

Benchmarking with Criterium, performance tips, and other tools

Deployment and DevOps

Introduction

Riemann - monitoring deliverance and slacking

Deploying Clojure with Docker

Clojure on Amazon Web Services

Customer Reviews

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Streaming access to provide high performance

This recipe will take a look at how to parse and write large amount of data. Since XML is probably the most verbose of data formats, we will look briefly at how to generate large amount of junk data and then how to process those in a memory efficient way.

Getting ready

The data.xml library is our library of choice here, so let's add it to the project.clj if it is not already:

[org.clojure/data.xml "0.1.0-beta1"]

We will also make use of the core Java streaming and zipping functions that are available in the JVM. We know we can access host functions just by importing them in the current namespace, so nothing more to prepare here.

How to do it...

So that's it. Let's go for a large dump of data onto our file system. We will create an XML element.

Streaming out

We get ready by pulling the proper namespaces for XML and for writing to streams:

(use 'clojure.data.xml) 
(use '[clojure.java.io :only [writer output-stream]])

Now, we can generate...

Clojure Programming Cookbook

Clojure Programming Cookbook

Overview of this book

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Current Title:

Clojure Programming Cookbook

Streaming access to provide high performance

Getting ready

How to do it...

Streaming out