Programming Crystal: Create High-Performance, Safe, Concurrent Apps

Cover....1 Table of Contents....7 Preface....11 Who This Book Is For....11 What’s in This Book....11 How to Read This Book....13 Conventions Used in This Book....14 Web Resources and Feedback....15 Downloading Sample Code....15 Acknowledgments....16 Part I—Getting Started....17 1. Diving into Crystal....18 A Programming Language for Humans and Computers....18 Slick As Ruby, But Way Faster....19 Almost As Fast As C....22 Speeding Up the Web....24 Talking to Databases....26 More Safety Through Types....27 No to the Billion-Dollar Mistake....28 Batteries Included....29 Putting Crystal to Good Use....30 A Company’s Story Crystallized: Red Panthers....31 Wrapping Up....33 2. Crystal Foundations....34 Using Basic Variables and Types....34 Variable Operations....37 Structuring Data with Container Types....38 Controlling the Flow....43 Using Methods....48 Organizing Code in Classes and Modules....49 Executing Code Concurrently Through Fibers....53 A Company’s Story Crystallized: Dev Demand....54 Wrapping Up....55 Part II—Building Blocks....56 3. Typing Variables and Controlling the Flow....57 Converting Data Between Types....58 Getting Input....60 Putting It Together—Converting Currencies 1....62 Exception Handling for Faulty Input....64 Chaining Methods....66 Getting Input from Command-Line Arguments....67 Using String Methods....68 Using Symbols as Identifiers....71 Using Enums....72 Using Regular Expressions....72 Putting It Together—Converting Currencies 2....73 Beyond Hashes and Arrays: More Composite Types....74 Nilable Types....76 Controlling the Flow and Types....78 A Company’s Story Crystallized: Linkfeed....81 Wrapping Up....82 4. Organizing Code in Methods and Procs....83 Passing Arguments....84 Returning Values....86 Working with Yield, Procs, and Blocks....88 Overloading and Multiple Dispatch....94 Using a Shorter Syntax for Exception Handling....97 Using Recursive Methods....98 A Company’s Story Crystallized: Duo Design....100 Wrapping Up....102 5. Using Classes and Structs....103 Converting a Ruby Class to Crystal....103 Structuring a Class....110 Applying Inheritance....113 Controlling Visibility....116 Working with Structs....121 Viewing the Type Hierarchy....123 Some Nice Tricks....124 A Company’s Story Crystallized: LI-COR Biosciences....128 Wrapping Up....129 6. Working with Modules....130 Combining Files with Require....130 Using Modules as Namespaces....133 Letting Modules Extend Themselves....135 Mixing in Modules....136 How the Compiler Finds Methods....137 Applying Built-In Modules....138 A Company’s Story Crystallized: Diploid....140 Wrapping Up....142 7. Managing Projects....143 Creating a Shard....143 Formatting Code....146 Documenting a Project....146 Writing Tests with Spec....148 Using External Libraries....152 Benchmarking Your Code....156 Deploying a Crystal App....158 A Company’s Story Crystallized: Diploid—Part 2....158 Wrapping Up....160 Part III—Advanced Crystal....161 8. Advanced Features....162 DRY Your Code with Macros....162 Low-Level Programming and C Bindings....167 Creating Concurrent Code....170 Accessing Databases....178 A Company’s Story Crystallized: NeuraLegion....182 Wrapping Up....183 9. Using Web Frameworks and Shards....184 Build Web Applications with the Kemal and Amber Frameworks....184 A Brief Tour of the Shard Ecosystem....198 A Company’s Story Crystallized: Kemal in Production....200 Wrapping Up and Afterword....201 Part IV—Appendices....202 A1. Setting Up a Crystal Environment....203 Working with Crystal Online....203 Installing Crystal on Your Machine....204 Compiling Code....205 Using Editors and IDEs....207 Working with Crystal Playground....210 Using Crystal Documentation....213 Wrapping Up....214 A2. Porting Ruby Code to Crystal....215 Ruby Extensions in Crystal....217 A3. Your Turn Answers....218 Chapter 2: Crystal Foundations....218 Chapter 3: Typing Variables and Controlling the Flow....219 Chapter 4: Organizing Code in Methods and Procs....220 Chapter 5: Using Classes and Structs....220 Chapter 6: Working with Modules....221 Chapter 7: Managing Projects....221 Chapter 8: Advanced Features....221 Chapter 9: Web Frameworks and the Shard Ecosystem....222 Appendix 1: Setting Up a Crystal Environment....222 Index....223 – SYMBOLS –....223 – A –....223 – B –....224 – C –....224 – D –....226 – E –....226 – F –....227 – G –....227 – H –....227 – I –....228 – J –....228 – K –....228 – L –....228 – M –....229 – N –....230 – O –....230 – P –....230 – Q –....231 – R –....231 – S –....232 – T –....233 – U –....234 – V –....234 – W –....234 – Y –....234