Interest in the Scala programming language continues to grow for many reasons. Scala embraces the functional programming style without abandoning the object-oriented paradigm, and it allows you to write programs more concisely than in Java. Because Scala runs on the JVM, it can access any Java library and is interoperable with familiar Java frameworks. Scala also makes it easier to leverage the full power of concurrency. Written for experienced Java, C++, or C# programmers who are new to Scala or functional programming, Scala for the Impatient, Second Edition, introduces the key Scala concepts and techniques you need in order to be productive quickly. It is the perfect introduction to the language, particularly for impatient readers who want to learn the fundamentals of Scala so they can start coding quickly. It doesn’t attempt to exhaustively list all the features of the language or make you suffer through long and contrived examples. Instead, carefully crafted examples and hands-on activities guide you through well-defined stages of competency, from basic to expert. This revised edition has been thoroughly updated for Scala 2.12 and reflects current Scala usage. It includes added coverage of recent Scala features, including string interpolation, dynamic invocation, implicit classes, and futures. Scala is a big language, but you can use it effectively without knowing all of its details intimately. This title provides precisely the information that you need to get started in compact, easy-to-understand chunks. Get started quickly with Scala’s interpreter, syntax, tools, and unique idioms Master core language features: functions, arrays, maps, tuples, packages, imports, exception handling, and more Become familiar with object-oriented programming in Scala: classes, inheritance, and traits Use Scala for real-world programming tasks: working with files, regular expressions, and XML Work with higher-order functions and the powerful Scala collections library Leverage Scala’s powerful pattern matching and case classes Create concurrent programs with Scala futures Implement domain-specific languages Understand the Scala type system Apply advanced “power tools,” such as annotations, implicits, and type classes Register your product at informit.com/register for convenient access to downloads, updates, and corrections as they become available.

Table of Contents:
Foreword to the First Edition xvii Preface xix About the Author xxi   Chapter 1: The Basics 1 1.1 The Scala Interpreter 1 1.2 Declaring Values and Variables 4 1.3 Commonly Used Types 5 1.4 Arithmetic and Operator Overloading 6 1.5 More about Calling Methods 8 1.6 The apply Method 9 1.7 Scaladoc 10 Exercises 15   Chapter 2: Control Structures and Functions 17 2.1 Conditional Expressions 18 2.2 Statement Termination 19 2.3 Block Expressions and Assignments 20 2.4 Input and Output 21 2.5 Loops 22 2.6 Advanced for Loops 24 2.7 Functions 25 2.8 Default and Named Arguments 26 2.9 Variable Arguments 26 2.10 Procedures 28 2.11 Lazy Values 28 2.12 Exceptions 29 Exercises 31   Chapter 3: Working with Arrays 35 3.1 Fixed-Length Arrays 35 3.2 Variable-Length Arrays: Array Buffers 36 3.3 Traversing Arrays and Array Buffers 37 3.4 Transforming Arrays 38 3.5 Common Algorithms 40 3.6 Deciphering Scaladoc 41 3.7 Multidimensional Arrays 42 3.8 Interoperating with Java 43 Exercises 44   Chapter 4: Maps and Tuples 47 4.1 Constructing a Map 48 4.2 Accessing Map Values 48 4.3 Updating Map Values 49 4.4 Iterating over Maps 50 4.5 Sorted Maps 50 4.6 Interoperating with Java 50 4.7 Tuples 51 4.8 Zipping 52 Exercises 52   Chapter 5: Classes 55 5.1 Simple Classes and Parameterless Methods 55 5.2 Properties with Getters and Setters 56 5.3 Properties with Only Getters 59 5.4 Object-Private Fields 60 5.5 Bean Properties 61 5.6 Auxiliary Constructors 62 5.7 The Primary Constructor 63 5.8 Nested Classes 66 Exercises 68   Chapter 6: Objects 71 6.1 Singletons 71 6.2 Companion Objects 72 6.3 Objects Extending a Class or Trait 73 6.4 The apply Method 73 6.5 Application Objects 74 6.6 Enumerations 75 Exercises 77   Chapter 7: Packages and Imports 79 7.1 Packages 80 7.2 Scope Rules 81 7.3 Chained Package Clauses 83 7.4 Top-of-File Notation 83 7.5 Package Objects 83 7.6 Package Visibility 84 7.7 Imports 85 7.8 Imports Can Be Anywhere 85 7.9 Renaming and Hiding Members 86 7.10 Implicit Imports 86 Exercises 87   Chapter 8: Inheritance 91 8.1 Extending a Class 91 8.2 Overriding Methods 92 8.3 Type Checks and Casts 93 8.4 Protected Fields and Methods 94 8.5 Superclass Construction 94 8.6 Overriding Fields 95 8.7 Anonymous Subclasses 97 8.8 Abstract Classes 97 8.9 Abstract Fields 97 8.10 Construction Order and Early Definitions 98 8.11 The Scala Inheritance Hierarchy 100 8.12 Object Equality 102 8.13 Value Classes 103 Exercises 105   Chapter 9: Files and Regular Expressions 109 9.1 Reading Lines 109 9.2 Reading Characters 110 9.3 Reading Tokens and Numbers 111 9.4 Reading from URLs and Other Sources 111 9.5 Reading Binary Files 112 9.6 Writing Text Files 112 9.7 Visiting Directories 112 9.8 Serialization 113 9.9 Process Control 114 9.10 Regular Expressions 116 9.11 Regular Expression Groups 117 Exercises 118   Chapter 10: Traits 121 10.1 Why No Multiple Inheritance? 121 10.2 Traits as Interfaces 123 10.3 Traits with Concrete Implementations 124 10.4 Objects with Traits 125 10.5 Layered Traits 125 10.6 Overriding Abstract Methods in Traits 127 10.7 Traits for Rich Interfaces 127 10.8 Concrete Fields in Traits 128 10.9 Abstract Fields in Traits 130 10.10 Trait Construction Order 130 10.11 Initializing Trait Fields 132 10.12 Traits Extending Classes 133 10.13 Self Types 134 10.14 What Happens under the Hood 135 Exercises 137   Chapter 11: Operators 141 11.1 Identifiers 142 11.2 Infix Operators 143 11.3 Unary Operators 143 11.4 Assignment Operators 144 11.5 Precedence 144 11.6 Associativity 145 11.7 The apply and update Methods 146 11.8 Extractors 147 11.9 Extractors with One or No Arguments 149 11.10 The unapplySeq Method 149 11.11 Dynamic Invocation 150 Exercises 153   Chapter 12: Higher-Order Functions 157 12.1 Functions as Values 157 12.2 Anonymous Functions 159 12.3 Functions with Function Parameters 160 12.4 Parameter Inference 160 12.5 Useful Higher-Order Functions 161 12.6 Closures 162 12.7 SAM Conversions 163 12.8 Currying 164 12.9 Control Abstractions 166 12.10 The return Expression 167 Exercises 168   Chapter 13: Collections 171 13.1 The Main Collections Traits 172 13.2 Mutable and Immutable Collections 173 13.3 Sequences 174 13.4 Lists 175 13.5 Sets 177 13.6 Operators for Adding or Removing Elements 178 13.7 Common Methods 180 13.8 Mapping a Function 182 13.9 Reducing, Folding, and Scanning 184 13.10 Zipping 187 13.11 Iterators 188 13.12 Streams 189 13.13 Lazy Views 190 13.14 Interoperability with Java Collections 191 13.15 Parallel Collections 193 Exercises 194   Chapter 14: Pattern Matching and Case Classes 197 14.1 A Better Switch 198 14.2 Guards 199 14.3 Variables in Patterns 199 14.4 Type Patterns 200 14.5 Matching Arrays, Lists, and Tuples 201 14.6 Extractors 202 14.7 Patterns in Variable Declarations 203 14.8 Patterns in for Expressions 204 14.9 Case Classes 205 14.10 The copy Method and Named Parameters 205 14.11 Infix Notation in case Clauses 206 14.12 Matching Nested Structures 207 14.13 Are Case Classes Evil? 208 14.14 Sealed Classes 209 14.15 Simulating Enumerations 209 14.16 The Option Type 210 14.17 Partial Functions 211 Exercises 212   Chapter 15: Annotations 215 15.1 What Are Annotations? 216 15.2 What Can Be Annotated? 216 15.3 Annotation Arguments 217 15.4 Annotation Implementations 218 15.5 Annotations for Java Features 219 15.6 Annotations for Optimizations 222 15.7 Annotations for Errors and Warnings 226 Exercises 227   Chapter 16: XML Processing 229 16.1 XML Literals 230 16.2 XML Nodes 230 16.3 Element Attributes 232 16.4 Embedded Expressions 233 16.5 Expressions in Attributes 234 16.6 Uncommon Node Types 235 16.7 XPath-like Expressions 235 16.8 Pattern Matching 237 16.9 Modifying Elements and Attributes 238 16.10 Transforming XML 239 16.11 Loading and Saving 239 16.12 Namespaces 242 Exercises 243   Chapter 17: Futures 247 17.1 Running Tasks in the Future 248 17.2 Waiting for Results 250 17.3 The Try Class 251 17.4 Callbacks 251 17.5 Composing Future Tasks 252 17.6 Other Future Transformations 255 17.7 Methods in the Future Object 256 17.8 Promises 258 17.9 Execution Contexts 260 Exercises 260   Chapter 18: Type Parameters 265 18.1 Generic Classes 266 18.2 Generic Functions 266 18.3 Bounds for Type Variables 266 18.4 View Bounds 268 18.5 Context Bounds 268 18.6 The ClassTag Context Bound 269 18.7 Multiple Bounds 269 18.8 Type Constraints 269 18.9 Variance 271 18.10 Co- and Contravariant Positions 272 18.11 Objects Can’t Be Generic 274 18.12 Wildcards 275 Exercises 275   Chapter 19: Advanced Types 279 19.1 Singleton Types 280 19.2 Type Projections 281 19.3 Paths 282 19.4 Type Aliases 283 19.5 Structural Types 283 19.6 Compound Types 284 19.7 Infix Types 285 19.8 Existential Types 286 19.9 The Scala Type System 287 19.10 Self Types 288 19.11 Dependency Injection 289 19.12 Abstract Types 291 19.13 Family Polymorphism 293 19.14 Higher-Kinded Types 296 Exercises 299   Chapter 20: Parsing 303 20.1 Grammars 304 20.2 Combining Parser Operations 305 20.3 Transforming Parser Results 307 20.4 Discarding Tokens 308 20.5 Generating Parse Trees 309 20.6 Avoiding Left Recursion 310 20.7 More Combinators 311 20.8 Avoiding Backtracking 314 20.9 Packrat Parsers 314 20.10 What Exactly Are Parsers? 315 20.11 Regex Parsers 316 20.12 Token-Based Parsers 317 20.13 Error Handling 319 Exercises 320   Chapter 21: Implicits 323 21.1 Implicit Conversions 324 21.2 Using Implicits for Enriching Existing Classes 324 21.3 Importing Implicits 325 21.4 Rules for Implicit Conversions 326 21.5 Implicit Parameters 328 21.6 Implicit Conversions with Implicit Parameters 329 21.7 Context Bounds 329 21.8 Type Classes 331 21.9 Evidence 333 21.10 The @implicitNotFound Annotation 334 21.11 CanBuildFrom Demystified 334 Exercises 336   Index 338