Getting Clojure : Build Your Functional Skills One Idea at a Time

Behind every programming language lies a vision of how programs should be built. The vision behind Clojure is of a radically simple language framework holding together a sophisticated collection of programming features. Learning Clojure involves much more than just learning the mechanics of the language. To really get Clojure you need to understand the ideas underlying this structure of framework and features. You need this book: an accessible introduction to Clojure that focuses on the ideas behind the language as well as the practical details of writing code. Clojure attracts developers on the cutting edge and is arguably the best language for learning to program in the functional style without compromise. But this comes with a steep learning curve. Getting Clojure directly addresses this by teaching you how to think functionally as it teaches you the language. You'll learn about Clojure's powerful data structures and high-level functions, but you'll also learn what it means for a language to be functional, and how to think in Clojure's functional way. Each chapter of Getting Clojure takes a feature or two or three from the language, explains the syntax and the mechanics behind that feature so that you can make it work before digging into the deeper questions: What is the thinking behind the feature? And how does it fit in with the rest of the language? In Getting Clojure you'll learn Clojure's very simple syntax, but you'll also learn why that syntax is integral the way the language is constructed. You'll discover that most data structures in Clojure are immutable, but also why that leads to more reliable programs. And you'll see how easy it is to write Clojure functions and also how you can use those functions to build complex and capable systems. With real-world examples of how working Clojure programmers use the language, Getting Clojure will help you see the challenges of programming through the eye of experienced Clojure developers. What You Need: You will need to some background in programming. To follow along with the examples in the book, you will need Java 6 or new, Clojure 1.8 or 1.9, and Leiningen 2. Cover Table of Contents Acknowledgments Preface Who Is This Book For? How Is This Book Organized? About the Code Examples Online Resources Part I—Basics 1. Hello, Clojure The Very Basics Arithmetic Not Variable Assignment, but Close A Function of Your Own In the Wild Staying Out of Trouble Wrapping Up 2. Vectors and Lists One Thing After Another A Toolkit of Functions Growing Your Vectors Lists Lists versus Vectors Staying Out of Trouble In the Wild Wrapping Up 3. Maps, Keywords, and Sets This Goes with That Keywords Changing Your Map Without Changing It Other Handy Map Functions Sets In the Wild Staying Out of Trouble Wrapping Up 4. Logic The Fundamental If Asking Questions Truthy and Falsy Do and When Dealing with Multiple Conditions Throwing and Catching In the Wild Staying Out of Trouble Wrapping Up 5. More Capable Functions One Function, Different Parameters Arguments with Wild Abandon Multimethods Deeply Recursive Docstrings Pre and Post Conditions Staying Out of Trouble In the Wild Wrapping Up 6. Functional Things Functions Are Values Functions on the Fly A Functional Toolkit Function Literals In the Wild Staying Out of Trouble Wrapping Up 7. Let A Local, Temporary Place for Your Stuff Let Over Fn Variations on the Theme In the Wild Staying Out of Trouble Wrapping Up 8. Def, Symbols, and Vars A Global, Stable Place for Your Stuff Symbols Are Things Bindings Are Things Too Varying Your Vars Staying Out of Trouble In the Wild Wrapping Up 9. Namespaces A Place for Your Vars Loading Namespaces A Namespace of Your Own As and Refer Namespaces, Symbols, and Keywords In the Wild Staying Out of Trouble Wrapping Up Part II—Intermediate 10. Sequences One Thing After Another A Universal Interface A Rich Toolkit ... ... Made Richer with Functional Values Map Reduce Composing a Solution Other Sources of Sequences In the Wild Staying Out of Trouble Wrapping Up 11. Lazy Sequences Sequences Without End More Interesting Laziness Lazy Friends Laziness in Practice Behind the Scenes Staying Out of Trouble In the Wild Wrapping Up 12. Destructuring Pry Open Your Data Getting Less than Everything Destructuring in Sequence Destructuring Function Arguments Digging into Maps Diving into Nested Maps The Final Frontier: Mixing and Matching Going Further Staying Out of Trouble In the Wild Wrapping Up 13. Records and Protocols The Trouble with Maps Striking a More Specific Bargain with Records Records Are Maps The Record Advantage Protocols Decentralized Polymorphism Record Confusion In the Wild Staying Out of Trouble Wrapping Up 14. Tests Spotting Bugs with clojure.test Testing Namespaces and Projects Property-Based Testing Checking Properties Staying Out of Trouble In the Wild Wrapping Up 15. Spec This Is the Data You’re Looking For Spec’ing Collections Registering Specs Spec’ing Maps (Again) Why? Why? Why? Function Specs Spec-Driven Tests Staying Out of Trouble In the Wild Wrapping Up Part III—Advanced 16. Interoperating with Java A Peek at Java ... ... And Back to Clojure Packages Class Methods and Fields In the Wild Staying Out of Trouble Wrapping Up 17. Threads, Promises, and Futures Great Power ... ... And Great Responsibility Good Fences Make Happy Threads Promise Me a Result A Value with a Future Staying Out of Trouble In the Wild Wrapping up 18. State It’s Made of Atoms Swapping Maps Refs: Team-Oriented Atoms Agents Choose Wisely In the Wild Staying Out of Trouble Wrapping Up 19. Read and Eval You Got Data On My Code! Reading and Evaluating The Homoiconic Advantage An Eval of Your Own In the Wild Staying Out of Trouble Wrapping Up 20. Macros There Are Three Kinds of Numbers in the World Macros to the Rescue Easier Macros with Syntax Quoting In the Wild Staying Out of Trouble Wrapping Up 21. Conclusion Index – SYMBOLS – – DIGITS – – A – – B – – C – – D – – E – – F – – G – – H – – I – – J – – K – – L – – M – – N – – O – – P – – Q – – R – – S – – T – – U – – V – – W – – Z – "Learning Clojure involves much more than just learning the mechanics. To really get Clojure you need to understand the ideas underlying its structure and features. This accessible introduction to Clojure focuses on the ideas behind the language as well as the practical details of writing code. Explore the syntax and the mechanics behind each language feature, and then dig into the deeper questions: What is the thinking behind the feature? How does it fit with the rest of the language? Learn Clojure's simple syntax, and why that syntax is integral to the way the language is constructed. Discover why Clojure's immutable data structures lead to more reliable programs. See how easy it is to write Clojure functions and how you can use them to build complex and capable systems. Use real-world examples to see the challenges of programming through the eye of experienced Clojure developers."-- Provided by publisher