book

Programming Scala

by Dean Wampler, Alex Payne

September 2009

Intermediate to advanced

446 pages

12h 37m

English

O'Reilly Media, Inc.

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Dedication
A Note Regarding Supplemental Files
Foreword
Preface
Welcome to Programming ScalaConventions Used in This BookUsing Code ExamplesGetting the Code ExamplesSafari® Books OnlineHow to Contact UsAcknowledgments
1. Zero to Sixty: Introducing Scala
Why Scala?If You Are a Java Programmer…If You Are a Ruby, Python, etc. Programmer…Introducing ScalaThe Seductions of ScalaInstalling ScalaFor More InformationA Taste of ScalaA Taste of ConcurrencyRecap and What’s Next
2. Type Less, Do More
In This ChapterSemicolonsVariable DeclarationsMethod DeclarationsMethod Default and Named Arguments (Scala Version 2.8)Nesting Method DefinitionsInferring Type InformationLiteralsInteger LiteralsFloating-Point LiteralsBoolean LiteralsCharacter LiteralsString LiteralsSymbol LiteralsTuplesOption, Some, and None: Avoiding nullsOrganizing Code in Files and NamespacesImporting Types and Their MembersImports are RelativeAbstract Types And Parameterized TypesReserved WordsRecap and What’s Next
3. Rounding Out the Essentials
Operator? Operator?Syntactic SugarMethods Without Parentheses and DotsPrecedence RulesDomain-Specific LanguagesScala if StatementsScala for ComprehensionsA Dog-Simple ExampleFilteringYieldingExpanded ScopeOther Looping ConstructsScala while LoopsScala do-while LoopsGenerator ExpressionsConditional OperatorsPattern MatchingA Simple MatchVariables in MatchesMatching on TypeMatching on SequencesMatching on Tuples (and Guards)Matching on Case ClassesMatching on Regular ExpressionsBinding Nested Variables in Case ClausesUsing try, catch, and finally ClausesConcluding Remarks on Pattern MatchingEnumerationsRecap and What’s Next
4. Traits
Introducing TraitsTraits As MixinsStackable TraitsConstructing TraitsClass or Trait?Recap and What’s Next
5. Basic Object-Oriented Programming in Scala
Class and Object BasicsParent ClassesConstructors in ScalaCalling Parent Class ConstructorsNested ClassesVisibility RulesPublic VisibilityProtected VisibilityPrivate VisibilityScoped Private and Protected VisibilityFinal Thoughts on VisibilityRecap and What’s Next
6. Advanced Object-Oriented Programming In Scala
Overriding Members of Classes and TraitsAttempting to Override final DeclarationsOverriding Abstract and Concrete MethodsOverriding Abstract and Concrete FieldsOverriding Abstract and Concrete Fields in TraitsOverriding Abstract and Concrete Fields in ClassesOverriding Abstract TypesWhen Accessor Methods and Fields Are Indistinguishable: The Uniform Access PrincipleCompanion ObjectsApplyUnapplyApply and UnapplySeq for CollectionsCompanion Objects and Java Static MethodsCase ClassesSyntactic Sugar for Binary OperationsThe copy Method in Scala Version 2.8Case Class InheritanceEquality of ObjectsThe equals MethodThe == and != MethodsThe ne and eq MethodsArray Equality and the sameElements MethodRecap and What’s Next

7. The Scala Object System
The Predef ObjectClasses and Objects: Where Are the Statics?Package ObjectsSealed Class HierarchiesThe Scala Type HierarchyLinearization of an Object’s HierarchyRecap and What’s Next
8. Functional Programming in Scala
What Is Functional Programming?Functions in MathematicsVariables that Aren’tFunctional Programming in ScalaFunction Literals and ClosuresPurity Inside Versus OutsideRecursionTail Calls and Tail-Call OptimizationTrampoline for Tail CallsFunctional Data StructuresLists in Functional ProgrammingMaps in Functional ProgrammingSets in Functional ProgrammingOther Data Structures in Functional ProgrammingTraversing, Mapping, Filtering, Folding, and ReducingTraversalMappingFilteringFolding and ReducingFunctional OptionsPattern MatchingPartial FunctionsCurryingImplicitsImplicit ConversionsImplicit Function ParametersFinal Thoughts on ImplicitsCall by Name, Call by ValueLazy ValsRecap: Functional Component Abstractions
9. Robust, Scalable Concurrency with Actors
The Problems of Shared, Synchronized StateActorsActors in AbstractActors in ScalaSending Messages to ActorsThe MailboxActors in DepthEffective ActorsTraditional Concurrency in Scala: Threading and EventsOne-Off ThreadsUsing java.util.concurrentEventsRecap and What’s Next
10. Herding XML in Scala
Reading XMLExploring XMLLooping and Matching XMLWriting XMLA Real-World ExampleRecap and What’s Next
11. Domain-Specific Languages in Scala
Internal DSLsA Payroll Internal DSLInfix Operator NotationImplicit Conversions and User-Defined TypesApply MethodsPayroll Rules DSL ImplementationInternal DSLs: Final ThoughtsExternal DSLs with Parser CombinatorsAbout Parser CombinatorsA Payroll External DSLA Scala Implementation of the External DSL GrammarGenerating Paychecks with the External DSLInternal Versus External DSLs: Final ThoughtsRecap and What’s Next
12. The Scala Type System
Reflecting on TypesUnderstanding Parameterized TypesManifestsParameterized MethodsVariance Under InheritanceVariance of Mutable TypesVariance In Scala Versus JavaImplementation NotesType BoundsUpper Type BoundsLower Type BoundsA Closer Look at ListsViews and View BoundsNothing and NullUnderstanding Abstract TypesParameterized Types Versus Abstract TypesPath-Dependent TypesC.thisC.superpath.xValue TypesType DesignatorsTuplesParameterized TypesAnnotated TypesCompound TypesInfix TypesFunction TypesType ProjectionsSingleton TypesSelf-Type AnnotationsStructural TypesExistential TypesInfinite Data Structures and LazinessRecap and What’s Next
13. Application Design
AnnotationsEnumerations Versus Pattern MatchingThoughts On Annotations and EnumerationsEnumerations Versus Case Classes and Pattern MatchingUsing Nulls Versus OptionsOptions and for ComprehensionsExceptions and the AlternativesScalable AbstractionsFine-Grained Visibility RulesMixin CompositionSelf-Type Annotations and Abstract Type MembersEffective Design of TraitsDesign PatternsThe Visitor Pattern: A Better AlternativeDependency Injection in Scala: The Cake PatternBetter Design with Design By ContractRecap and What’s Next
14. Scala Tools, Libraries, and IDE Support
Command-Line Toolsscalac Command-Line ToolThe scala Command-Line ToolLimitations of scala versus scalacThe scalap, javap, and jad Command-Line ToolsThe scaladoc Command-Line ToolThe sbaz Command-Line ToolThe fsc Command-Line ToolBuild ToolsIntegration with IDEsEclipseInstalling the Scala pluginDeveloping Scala applicationsIntelliJInstalling the Scala pluginsDeveloping Scala applicationsNetBeansInstalling the Scala pluginsDeveloping Scala applicationsText EditorsTest-Driven Development in ScalaScalaTestSpecsScalaCheckOther Notable Scala Libraries and ToolsLiftScalazScalaxMetaScalaJavaRebelMiscellaneous Smaller LibrariesJava InteroperabilityJava and Scala GenericsUsing Scala Functions in JavaJavaBean PropertiesAnyVal Types and Java PrimitivesScala Names in Java CodeJava Library InteroperabilityAspectJThe Spring FrameworkTerracottaHadoopRecap and What’s Next
A. References
Glossary
Index
About the Authors
Colophon
Copyright

Overview

Learn how to be more productive with Scala, a new multi-paradigm language for the Java Virtual Machine (JVM) that integrates features of both object-oriented and functional programming. With this book, you'll discover why Scala is ideal for highly scalable, component-based applications that support concurrency and distribution.

Programming Scala clearly explains the advantages of Scala as a JVM language. You'll learn how to leverage the wealth of Java class libraries to meet the practical needs of enterprise and Internet projects more easily. Packed with code examples, this book provides useful information on Scala's command-line tools, third-party tools, libraries, and available language-aware plugins for editors and IDEs.

Learn how Scala's succinct and flexible code helps you program faster
Discover the notable improvements Scala offers over Java's object model
Get a concise overview of functional programming, and learn how Scala's support for it offers a better approach to concurrency
Know how to use mixin composition with traits, pattern matching, concurrency with Actors, and other essential features
Take advantage of Scala's built-in support for XML
Learn how to develop domain-specific languages
Understand the basics for designing test-driven Scala applications

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