Programming Clojure

Description

Drowning in unnecessary complexity, unmanaged state, and tangles of spaghetti code? In the best tradition of Lisp, Clojure gets out of your way so you can focus on expressing simple solutions to hard problems. Clojure cuts through complexity by providing a set of composable tools--immutable data, functions, macros, and the interactive REPL. Written by members of the Clojure core team, this book is the essential, definitive guide to Clojure. This new edition includes information on all the newest features of Clojure, such as transducers and specs. Clojure joins the flexibility and agility of Lisp with the reach, stability, and performance of Java. Combine Clojure's tools for maximum effectiveness as you work with immutable data, functional programming, and safe concurrency to write programs that solve real-world problems. Start by reading and understanding Clojure syntax and see how Clojure is evaluated. From there, find out about the sequence abstraction, which combines immutable collections with functional programming to create truly reusable data transformation code. Clojure is a functional language; learn how to write programs in a functional style, and when and how to use recursion to your advantage. Discover Clojure's unique approach to state and identity, techniques for polymorphism and open systems using multimethods and protocols, and how to leverage Clojure's metaprogramming capabilities via macros. Finally, put all the pieces together in a real program. New to this edition is coverage of Clojure's spec library, one of the most interesting new features of Clojure for describing both data and functions. You can use Clojure spec to validate data, destructure data, explain invalid data, and generate large numbers of tests to verify the correctness of your code. With this book, you'll learn how to think in Clojure, and how to take advantage of its combined strengths to build powerful programs quickly. What You Need: Java 6 or higherClojure 1.9 Acknowledgments......Page 10 Introduction......Page 11 Who This Book Is For......Page 12 What’s in This Book......Page 13 How to Read This Book......Page 15 Notation Conventions......Page 17 Web Resources and Feedback......Page 19 Downloading Sample Code......Page 20 1. Getting Started......Page 21 Simplicity and Power in Action......Page 22 Clojure Coding Quick Start......Page 31 Navigating Clojure Libraries......Page 37 Wrapping Up......Page 41 2. Exploring Clojure......Page 42 Reading Clojure......Page 43 Functions......Page 50 Vars, Bindings, and Namespaces......Page 56 Metadata......Page 63 Calling Java......Page 65 Comments......Page 69 Flow Control......Page 70 Where’s My for Loop?......Page 74 Wrapping Up......Page 78 3. Unifying Data with Sequences......Page 79 Everything Is a Sequence......Page 81 Using the Sequence Library......Page 86 Lazy and Infinite Sequences......Page 96 Clojure Makes Java Seq-able......Page 99 Calling Structure-Specific Functions......Page 105 Wrapping Up......Page 114 4. Functional Programming......Page 115 Functional Programming Concepts......Page 116 How to Be Lazy......Page 121 Lazier Than Lazy......Page 130 Recursion Revisited......Page 136 Eager Transformations......Page 146 Wrapping Up......Page 151 5. Specifications......Page 152 Defining Specs......Page 155 Validating Data......Page 157 Validating Functions......Page 165 Generative Function Testing......Page 173 Wrapping Up......Page 178 6. State and Concurrency......Page 179 Concurrency, Parallelism, and Locking......Page 180 Refs and Software Transactional Memory......Page 182 Use Atoms for Uncoordinated, Synchronous Updates......Page 189 Use Agents for Asynchronous Updates......Page 191 Managing Per-Thread State with Vars......Page 197 A Clojure Snake......Page 202 Wrapping Up......Page 213 7. Protocols and Datatypes......Page 214 Programming to Abstractions......Page 215 Interfaces......Page 219 Protocols......Page 221 Datatypes......Page 226 Records......Page 232 reify......Page 238 Wrapping Up......Page 239 8. Macros......Page 240 When to Use Macros......Page 241 Writing a Control Flow Macro......Page 242 Making Macros Simpler......Page 249 Taxonomy of Macros......Page 255 Wrapping Up......Page 265 9. Multimethods......Page 266 Living Without Multimethods......Page 267 Defining Multimethods......Page 270 Moving Beyond Simple Dispatch......Page 274 Creating Ad Hoc Taxonomies......Page 276 When Should I Use Multimethods?......Page 281 Wrapping Up......Page 285 10. Java Interop......Page 286 Creating Java Objects in Clojure......Page 287 Calling Clojure From Java......Page 292 Exception Handling......Page 293 Optimizing for Performance......Page 298 A Real-World Example......Page 308 Wrapping Up......Page 312 11. Building an Application......Page 313 Getting Started......Page 314 Developing the Game Loop......Page 315 Representing Progress......Page 317 Implementing Players......Page 319 Interactive Play......Page 323 Documenting and Testing Your Game......Page 327 Farewell......Page 332 Bibliography......Page 333