book

Think Perl 6

by Laurent Rosenfeld, Allen B. Downey

May 2017

Beginner

466 pages

11h 12m

English

O'Reilly Media, Inc.

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Preface
The Aim of This BookThe History of This BookConventions Used in This BookUsing Code ExamplesO’Reilly SafariHow to Contact UsAcknowledgmentsContributor List
I. Starting with the Basics
1. The Way of the Program
What Is a Program?Running Perl 6The First ProgramArithmetic OperatorsValues and TypesFormal and Natural LanguagesDebuggingGlossaryExercises
2. Variables, Expressions, and Statements
Assignment StatementsVariable NamesExpressions and StatementsScript ModeOne-Liner ModeOrder of OperationsString OperationsCommentsDebuggingGlossaryExercises
3. Functions
Function CallsFunctions and MethodsMath FunctionsCompositionAdding New Functions (a.k.a. Subroutines)Definitions and UsesFlow of ExecutionParameters and ArgumentsVariables and Parameters Are LocalStack DiagramsFruitful Functions and Void FunctionsFunction SignaturesImmutable and Mutable ParametersFunctions and Subroutines as First-Class CitizensWhy Functions and Subroutines?DebuggingGlossaryExercises
4. Loops, Conditionals, and Recursion
Integer Division and ModuloBoolean expressionsLogical OperatorsConditional ExecutionAlternative ExecutionChained ConditionalsNested Conditionalsif Conditionals as Statement ModifiersUnless Conditional Statementfor LoopsRecursionStack Diagrams for Recursive SubroutinesInfinite RecursionKeyboard InputProgram Arguments and the MAIN SubroutineDebuggingGlossaryExercises
5. Fruitful Subroutines
Return ValuesIncremental DevelopmentCompositionBoolean FunctionsA Complete Programming LanguageMore RecursionLeap of FaithOne More ExampleChecking TypesMulti SubroutinesDebuggingGlossaryExercises
6. Iteration
Assignment Versus EqualityReassignmentUpdating VariablesThe while StatementLocal Variables and Variable ScopingControl Flow Statements (last, next, etc.)Square RootsAlgorithmsDebuggingGlossaryExercises
7. Strings
A String Is a SequenceCommon String OperatorsString LengthSearching for a Substring Within the StringExtracting a Substring from a StringA Few Other Useful String Functions or MethodsString Traversal with a while or for LoopLooping and CountingRegular Expressions (Regexes)Using RegexesBuilding your Regex PatternsLiteral MatchingWildcards and Character ClassesQuantifiersAnchors and AssertionsAlternationGrouping and CapturingAdverbs (a.k.a. Modifiers)Exercises on RegexesPutting It All TogetherExtracting DatesExtracting an IP AddressSubstitutionsThe subst MethodThe s/search/replace/ ConstructUsing CapturesAdverbsDebuggingGlossaryExercises
8. Case Study: Word Play
Reading from and Writing to FilesReading Word ListsExercisesSearchWords Longer Than 20 Characters (Solution)Words with No “e” (Solution)Avoiding Other Letters (Solution)Using Only Some Letters (Solution)Using All Letters of a List (Solution)Alphabetic Order (Solution)Another Example of Reduction to a Previously Solved ProblemDebuggingGlossaryExercises

9. Arrays and Lists
Lists and Arrays Are SequencesArrays Are MutableAdding New Elements to an Array or Removing SomeStacks and QueuesOther Ways to Modify an ArrayTraversing a ListNew Looping ConstructsMap, Filter, and ReduceReducing a List to a ValueThe Reduction MetaoperatorMapping a List to Another ListFiltering the Elements of a ListHigher-Order Functions and Functional ProgrammingFixed-Size, Typed, and Shaped ArraysMultidimensional ArraysSorting Arrays or ListsMore Advanced Sorting TechniquesDebuggingGlossaryExercises
10. Hashes
A Hash Is a MappingCommon Operations on HashesHash as a Collection of CountersLooping and HashesReverse LookupTesting for ExistenceHash Keys Are UniqueHashes and ArraysMemosHashes as Dispatch TablesGlobal VariablesDebuggingGlossaryExercises
11. Case Study: Data Structure Selection
The Ternary Conditional OperatorThe given ... when “Switch” StatementSubroutine Named and Optional ParametersNamed ParametersOptional ParametersWord Frequency AnalysisRandom NumbersWord HistogramMost Common WordsOptional ParametersHash SubtractionConstructing New OperatorsSets, Bags, and MixesRandom WordsMarkov AnalysisData StructuresBuilding Your Own Data StructuresLinked ListsTreesBinary HeapsDebuggingGlossaryExercises: Huffman CodingVariable-Length CodesThe Frequency TableBuilding the Huffman Code
II. Moving Forward
12. Classes and Objects
Objects, Methods, and Object-Oriented ProgrammingProgrammer-Defined TypesAttributesCreating MethodsRectangles and Object CompositionInstances as Return ValuesInheritanceThe Pixel ClassThe MovablePoint ClassMultiple Inheritance: Attractive, but Is It Wise?Roles and CompositionClasses and Roles: An ExampleRole Composition and Code ReuseRoles, Classes, Objects, and TypesMethod DelegationPolymorphismEncapsulationPrivate MethodsConstructing Objects with Private AttributesInterface and ImplementationObject-Oriented Programming: A TaleThe Fable of the ShepherdThe MoralDebuggingThe Perl 6 DebuggerGetting Some HelpStepping Through the CodeStopping at the Right Place with BreakpointsLogging Information with Trace PointsStepping Through a Regex MatchGlossary
13. Regexes and Grammars
A Brief RefresherDeclarative ProgrammingCapturesNamed Rules (a.k.a. Subrules)GrammarsGrammar InheritanceActions ObjectsA Grammar for Parsing JSONThe JSON FormatOur JSON SampleWriting the JSON Grammar Step by StepThe JSON GrammarAdding ActionsInheritance and Mutable GrammarsDebuggingGlossaryExercise: A Grammar for an Arithmetic Calculator
14. Functional Programming in Perl
Higher-Order FunctionsA Refresher on Functions as First-Class ObjectsAnonymous Subroutines and LambdasClosuresList Processing and Pipeline ProgrammingFeed and Backward Feed OperatorsThe Reduction MetaoperatorThe HyperoperatorThe Cross (X) and Zip (Z) OperatorsList Operators: A SummaryCreating New OperatorsCreating Your Own Map-Like FunctionsCustom versions of map, grep, etc.Our Own Version of a Sort FunctionAn Iterator Version of mapAn Iterator Version of grepThe gather and take ConstructLazy Lists and the Sequence OperatorThe Sequence OperatorInfinite ListsUsing an Explicit GeneratorCurrying and the Whatever OperatorCreating a Curried SubroutineCurrying an Existing Subroutine with the assuming MethodCurrying with the Whatever Star ParameterUsing a Functional Programming StyleThe Merge Sort AlgorithmA Nonfunctional Implementation of Merge SortA Functional Implementation of Merge SortDebuggingGlossaryExercise: Quick Sort
15. Some Final Advice
Make It Clear, Keep It SimpleDos and Don’tsUse IdiomsWhat’s Next?
A. Solutions to the Exercises
Exercises of Chapter 3: Functions and SubroutinesExercise 3-1: Subroutine right-justifyExercise 3-2: Subroutine do-twiceExercise 3-3: Subroutine print-gridExercises of Chapter 4: Conditionals and RecursionExercise Suggested in “Stack Diagrams for Recursive Subroutines”: Subroutine do-n-timesExercise 4-1: Days, Hours, Minutes, and SecondsExercise 4-2: Fermat’s TheoremExercise 4-3: Is It a Triangle?Exercise 4-4: The Fibonacci NumbersExercise 4-5: The recurse SubroutineExercises of Chapter 5: Fruitful FunctionsExercise: CompareExercise: HypotenuseExercise: Chained Relational OperatorsExercise 5-2: The Ackermann FunctionExercise 5-3: PalindromesExercise 5-4: PowersExercise 5-5: Finding the GCD of Two NumbersExercises of Chapter 6: IterationExercise 6-1: Square RootExercise 6-2: Pi EstimateExercises of Chapter 7: StringsExercise: String TraversalExercise: The DucklingsExercise: Counting the Letters of a StringExercise: Simulating a Regex with a LoopExercise: Regex ExercisesExercise: is-reverse SubroutineExercise 7-1: Counting LettersExercise 7-2: Lowercase LettersExercise 7-3: Caesar’s CipherExercises of Chapter 8: Word PlayExercise 8-7: Consecutive Double LettersExercise 8-8: Palindromes in OdometersExercise 8-9: Palindromes in AgesExercises of Chapter 9: Arrays and ListsExercise: Implementing a QueueExercise: Other Ways to Modify an ArrayExercise: Mapping and Filtering the Elements of a ListExercise: Advanced Sorting TechniquesExercise 9-1: Nested SumExercise 9-2: Cumulative SumExercise 9-3: MiddleExercise 9-4: ChopExercise 9-5: Subroutine is-sortedExercise 9-6: Subroutine is-anagramExercise 9-7: Subroutine has-duplicatesExercise 9-8: Simulating the Birthday ParadoxExercise 9-9: Comparing push and unshiftExercise 9-10: Bisection Search in a ListExercise 9-11: Reverse PairsExercise 9-12: Interlocking WordsExercises of Chapter 10: HashesExercise: A Hash Is a MappingExercise 10-1: Storing the Word List into a HashExercise 10-2: Memoizing the Ackermann FunctionExercise 10-3: Finding Duplicates with a HashExercise 10-4: Rotate PairsExercise 10-5: HomophonesExercises of Chapter 11Exercise: The given ... when switch statementExercise: Constructing New OperatorsExercise: Sets, Bags, and MixesExercise: Random WordsExercise: Markov AnalysisExercise: The Huffman CodeExercises of Chapter 13: Regexes and GrammarsExercise 13-1: Getting the February Dates RightExercise: A Grammar for an Arithmetic CalculatorExercises of Chapter 14: Functional ProgrammingExercise: Making a Functional Implementation of Quick Sort
Index

Overview

Want to learn how to program and think like a computer scientist? This practical guide gets you started on your programming journey with the help of Perl 6, the younger sister of the popular Perl programming language. Ideal for beginners, this hands-on book includes over 100 exercises with multiple solutions, and more than 1,000 code examples so you can quickly practice what you learn. Experienced programmers—especially those who know Perl 5—will also benefit.

Divided into two parts, Think Perl 6 starts with basic concepts that every programmer needs to know, and then focuses on different programming paradigms and some more advanced programming techniques. With two semesters’ worth of lessons, this book is the perfect teaching tool for computer science beginners in colleges and universities.

Learn basic concepts including variables, expressions, statements, functions, conditionals, recursion, and loops
Understand commonly used basic data structures and the most useful algorithms
Dive into object-oriented programming, and learn how to construct your own types and methods to extend the language
Use grammars and regular expressions to analyze textual content
Explore how functional programming can help you make your code simpler and more expressive

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