Functional and Concurrent Programming Core Concepts and Features

Leverage Modern Language Constructs to Write High-Quality Code Faster

The functional and concurrent programming language features supported by modern languages can be challenging, even for experienced developers. These features may appear intimidating to OOP programmers because of a misunderstanding of how they work. Programmers first need to become familiar with the abstract concepts that underlie these powerful features.

In Functional and Concurrent Programming, Michel Charpentier introduces a core set of programming language constructs that will help you be productive in a variety of programming languages—now and in the future. Charpentier illustrates key concepts with numerous small, focused code examples, written in Scala, and with case studies that provide a thorough grounding in functional and concurrent programming skills. These skills will carry from language to language—including the most recent incarnations of Java. Using these features will enable developers and programmers to write high-quality code that is easier to understand, debug, optimize, and evolve.

Key topics covered include:

• Recursion and tail recursion
• Pattern matching and algebraic datatypes
• Persistent structures and immutability
• Higher-order functions and lambda expressions
• Lazy evaluation and streams
• Threads and thread pools
• Atomicity and locking
• Synchronization and thread-safe objects
• Lock-free, non-blocking patterns
• Futures, promises, and functional-concurrent programming

As a bonus, the book includes a discussion of common typing strategies used in modern programming languages, including type inference, subtyping, polymorphism, type classes, type bounds, and type variance.

Most of the code examples are in Scala, which includes many of the standard features of functional and concurrent programming; however, no prior knowledge of Scala is assumed. You should be familiar with concepts such as classes, methods, objects, types, variables, loops, and conditionals and have enough programming experience to not be distracted by simple matters of syntax.

Michel Charpentier is an associate professor with the Computer Science department at the University of New Hampshire (UNH). His interests over the years have ranged from distributed systems to formal verification and mobile sensor networks. He has been with UNH since 1999 and currently teaches courses in programming languages, concurrency, formal verification, and model-checking.

Foreword by Cay Horstmann   xxiii

Preface    xxv

Acknowledgments    xxxv

About the Author    xxxvii

Part I. Functional Programming    1

Chapter 1: Concepts of Functional Programming    3

     1.1 What Is Functional Programming?     3

     1.2 Functions    4

     1.3 From Functions to Functional Programming Concepts    6

     1.4 Summary    7

Chapter 2: Functions in Programming Languages     9

     2.1 Defining Functions     9

     2.2 Composing Functions     10

     2.3 Functions Defined as Methods     12

     2.4 Operators Defined as Methods     12

     2.5 Extension Methods   13

     2.6 Local Functions     14

     2.7 Repeated Arguments     15

     2.8 Optional Arguments     16

     2.9 Named Arguments     16

     2.10 Type Parameters     17

     2.11 Summary     19

Chapter 3: Immutability     21

     3.1 Pure and Impure Functions     21

     3.2 Actions     23

     3.3 Expressions Versus Statements     25

     3.4 Functional Variables     26

     3.5 Immutable Objects     28

     3.6 Implementation of Mutable State     29

     3.7 Functional Lists     31

     3.8 Hybrid Designs     32

     3.9 Updating Collections of Mutable/Immutable Objects     35

     3.10 Summary     36

Chapter 4: Case Study: Active–Passive Sets     39

     4.1 Object-Oriented Design     39

     4.2 Functional Values     41

     4.3 Functional Objects     43

     4.4 Summary     44

Chapter 5: Pattern Matching and Algebraic Data Types     47

     5.1 Functional Switch     47

     5.2 Tuples     48

     5.3 Options     50

     5.4 Revisiting Functional Lists     51

     5.5 Trees     53

     5.6 Illustration: List Zipper     56

     5.7 Extractors     59

     5.8 Summary     60

Chapter 6: Recursive Programming     63

     6.1 The Need for Recursion     63

     6.2 Recursive Algorithms     65

     6.3 Key Principles of Recursive Algorithms     67

     6.4 Recursive Structures     69

     6.5 Tail Recursion     71

     6.6 Examples of Tail Recursive Functions     73

     6.7 Summary     77

Chapter 7: Recursion on Lists     79

     7.1 Recursive Algorithms as Equalities     79

     7.2 Traversing Lists     80

     7.3 Returning Lists     82

     7.4 Building Lists from the Execution Stack     84

     7.5 Recursion on Multiple/Nested Lists     85

     7.6 Recursion on Sublists Other Than the Tail     88

     7.7 Building Lists in Reverse Order     90

     7.8 Illustration: Sorting     92

     7.9 Building Lists Efficiently     94

     7.10 Summary     96

Chapter 8: Case Study: Binary Search Trees     99

     8.1 Binary Search Trees     99

     8.2 Sets of Integers as Binary Search Trees     100

     8.3 Implementation Without Rebalancing     102

     8.4 Self-Balancing Trees     107

     8.5 Summary     113

Chapter 9: Higher-Order Functions     115

     9.1 Functions as Values     115

     9.2 Currying     118

     9.3 Function Literals     120

     9.4 Functions Versus Methods     123

     9.5 Single-Abstract-Method Interfaces     124

     9.6 Partial Application     125

     9.7 Closures     130

     9.8 Inversion of Control     133

     9.9 Summary     133

Chapter 10: Standard Higher-Order Functions     137

     10.1 Functions with Predicate Arguments     137

     10.2 map and foreach     140

     10.3 atMap     141

     10.4 fold and reduce     146

     10.5 iterate, tabulate, and unfold     148

     10.6 sortWith, sortBy, maxBy, and minBy     149

     10.7 groupBy and groupMap     150

     10.8 Implementing Standard Higher-Order Functions     152

     10.9 foreach, map, atMap, and for-Comprehensions     152

     10.10 Summary     155

Chapter 11: Case Study: File Systems as Trees     157

     11.1 Design Overview     157

     11.2 A Node-Searching Helper Function     158

     11.3 String Representation     158

     11.4 Building Trees     160

     11.5 Querying     164

     11.6 Navigation     168

     11.7 Tree Zipper     169

     11.8 Summary     172

Chapter 12: Lazy Evaluation     173

     12.1 Delayed Evaluation of Arguments     173

     12.2 By-Name Arguments     174

     12.3 Control Abstraction     176

     12.4 Internal Domain-Specifc Languages     179

     12.5 Streams as Lazily Evaluated Lists     180

     12.6 Streams as Pipelines     182

     12.7 Streams as Infinite Data Structures     184

     12.8 Iterators     184

     12.9 Lists, Streams, Iterators, and Views     187

     12.10 Delayed Evaluation of Fields and Local Variables     190

     12.11 Illustration: Subset-Sum     191

     12.12 Summary     193

Chapter 13: Handling Failures     195

     13.1 Exceptions and Special Values     195

     13.2 Using Option     197

     13.3 Using Try     198

     13.4 Using Either     199

     13.5 Higher-Order Functions and Pipelines     201

     13.6 Summary     204

Chapter 14: Case Study: Trampolines     205

     14.1 Tail-Call Optimization     205

     14.2 Trampolines for Tail-Calls     206

     14.3 Tail-Call Optimization in Java     207

     14.4 Dealing with Non-Tail-Calls     209

     14.5 Summary     213

A Brief Interlude     215

Chapter 15: Types (and Related Concepts)      217

     15.1 Typing Strategies     217

     15.2 Types as Sets     222

     15.3 Types as Services     223

     15.4 Abstract Data Types     224

     15.5 Type Inference     225

     15.6 Subtypes     229

     15.7 Polymorphism     232

     15.8 Type Variance     235

     15.9 Type Bounds     241

     15.10 Type Classes     245

     15.11 Summary     250

Part II. Concurrent Programming     253

Chapter 16: Concepts of Concurrent Programming     255

     16.1 Non-sequential Programs     255

     16.2 Concurrent Programming Concepts     258

     16.3 Summary     259

Chapter 17: Threads and Nondeterminism     261

     17.1 Threads of Execution     261

     17.2 Creating Threads Using Lambda Expressions     263

     17.3 Nondeterministic Behavior of Multithreaded Programs     263

     17.4 Thread Termination     264

     17.5 Testing and Debugging Multithreaded Programs     266

     17.6 Summary     268

Chapter 18: Atomicity and Locking     271

     18.1 Atomicity     271

     18.2 Non-atomic Operations     273

     18.3 Atomic Operations and Non-atomic Composition     274

     18.4 Locking     278

     18.5 Intrinsic Locks     279

     18.6 Choosing Locking Targets     281

     18.7 Summary     283

Chapter 19: Thread-Safe Objects     285

     19.1 Immutable Objects     285

     19.2 Encapsulating Synchronization Policies     286

     19.3 Avoiding Reference Escape     288

     19.4 Public and Private Locks     289

     19.5 Leveraging Immutable Types     290

     19.6 Thread-Safety     293

     19.7 Summary     295

Chapter 20: Case Study: Thread-Safe Queue     297

     20.1 Queues as Pairs of Lists     297

     20.2 Single Public Lock Implementation     298

     20.3 Single Private Lock Implementation     301

     20.4 Applying Lock Splitting     303

     20.5 Summary     305

Chapter 21: Thread Pools     307

     21.1 Fire-and-Forget Asynchronous Execution     307

     21.2 Illustration: Parallel Server     309

     21.3 Different Types of Thread Pools     312

     21.4 Parallel Collections     314

     21.5 Summary     318

Chapter 22: Synchronization     321

     22.1 Illustration of the Need for Synchronization     321

     22.2 Synchronizers     324

     22.3 Deadlocks     325

     22.4 Debugging Deadlocks with Thread Dumps     328

     22.5 The Java Memory Model     330

     22.6 Summary     335

Chapter 23: Common Synchronizers     337

     23.1 Locks     337

     23.2 Latches and Barriers     339

     23.3 Semaphores     341

     23.4 Conditions     343

     23.5 Blocking Queues     349

     23.6 Summary     353

Chapter 24: Case Study: Parallel Execution     355

     24.1 Sequential Reference Implementation     355

     24.2 One New Thread per Task     356

     24.3 Bounded Number of Threads     357

     24.4 Dedicated Thread Pool     359

     24.5 Shared Thread Pool     360

     24.6 Bounded Thread Pool     361

     24.7 Parallel Collections     362

     24.8 Asynchronous Task Submission Using Conditions     362

     24.9 Two-Semaphore Implementation     367

     24.10 Summary     368

Chapter 25: Futures and Promises     369

     25.1 Functional Tasks     369

     25.2 Futures as Synchronizers     371

     25.3 Timeouts, Failures, and Cancellation     374

     25.4 Future Variants     375

     25.5 Promises     375

     25.6 Illustration: Thread-Safe Caching     377

     25.7 Summary     379

Chapter 26: Functional-Concurrent Programming     381

     26.1 Correctness and Performance Issues with Blocking     381

     26.2 Callbacks     384

     26.3 Higher-Order Functions on Futures     385

     26.4 Function atMap on Futures     388

     26.5 Illustration: Parallel Server Revisited     390

     26.6 Functional-Concurrent Programming Patterns     393

     26.7 Summary     397

Chapter 27: Minimizing Thread Blocking     399

     27.1 Atomic Operations     399

     27.2 Lock-Free Data Structures     402

     27.3 Fork/Join Pools     405

     27.4 Asynchronous Programming     406

     27.5 Actors     407

     27.6 Reactive Streams     411

     27.7 Non-blocking Synchronization     412

     27.8 Summary     414

Chapter 28: Case Study: Parallel Strategies     417

     28.1 Problem Definition     417

     28.2 Sequential Implementation with Timeout     419

     28.3 Parallel Implementation Using invokeAny     420

     28.4 Parallel Implementation Using CompletionService     421

     28.5 Asynchronous Implementation with Scala Futures     422

     28.6 Asynchronous Implementation with CompletableFuture     426

     28.7 Caching Results from Strategies     427

     28.8 Summary     431

Appendix A. Features of Java and Kotlin     433

     A.1 Functions in Java and Kotlin     433

     A.2 Immutability     436

     A.3 Pattern Matching and Algebraic Data Types     437

     A.4 Recursive Programming     439

     A.5 Higher-Order Functions     440

     A.6 Lazy Evaluation     446

     A.7 Handling Failures     449

     A.8 Types     451

     A.9 Threads     453

     A.10 Atomicity and Locking     454

     A.11 Thread-Safe Objects     455

     A.12 Thread Pools     457

     A.13 Synchronization     459

     A.14 Futures and Functional-Concurrent Programming     460

     A.15 Minimizing Thread Blocking     461

Glossary     463

Index    465

The New copy of this book will include any supplemental materials advertised. Please check the title of the book to determine if it should include any access cards, study guides, lab manuals, CDs, etc.

The Used, Rental and eBook copies of this book are not guaranteed to include any supplemental materials. Typically, only the book itself is included. This is true even if the title states it includes any access cards, study guides, lab manuals, CDs, etc.