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Perl 6 Deep Dive

By : Shitov

3 (4)

Perl 6 Deep Dive

3 (4)

By: Shitov

Overview of this book

Perl is a family of high-level, general-purpose, interpreted, dynamic programming languages consisting of Perl 5 and Perl 6. Perl 6 helps developers write concise and declarative code that is easy to maintain. This book is an end-to-end guide that will help non-Perl developers get to grips with the language and use it to solve real-world problems. Beginning with a brief introduction to Perl 6, the first module in the book will teach you how to write and execute basic programs. The second module delves into language constructs, where you will learn about the built-in data types, variables, operators, modules, subroutines, and so on available in Perl 6. Here the book also delves deeply into data manipulation (for example, strings and text files) and you will learn how to create safe and correct Perl 6 modules. You will learn to create software in Perl by following the Object Oriented Paradigm. The final module explains in detail the incredible concurrency support provided by Perl 6. Here you will also learn about regexes, functional programming, and reactive programming in Perl 6. By the end of the book, with the help of a number of examples that you can follow and immediately run, modify, and use in practice, you will be fully conversant with the benefits of Perl 6.

Free Chapter

What is Perl 6?

What is Perl 6?

Origins of Perl 6

Differences from Perl 5

Perl 6 resources

Compilers

Working with Rakudo Star

Writing our Hello World program

Summary

Writing Code

Writing Code

Using Unicode

Whitespaces and unspaces

Comments

Creating Pod documentation

Phasers

Simple input and output

Summary

Working with Variables and Built-in Data Types

Working with Variables and Built-in Data Types

Using variables

Using simple built-in data types

Data types to manipulate date and time

Summary

Working with Operators

Working with Operators

Operator classification

Operators in Perl 6

Meta-operators in Perl 6

User-defined operators

Summary

Control Flow

Control Flow

Understanding code blocks and variable scoping

Conditional checks

Using loops

Executing code once

Collecting data with gather and take

Setting the topic with given

Summary

Subroutines

Subroutines

Creating and calling subroutines

Type constraints

Multi subs

Nested subroutines

Creating operators

Passing functions as arguments

Anonymous subs

Summary

Modules

Modules

Creating a module

Using modules

Introspection

Using zef

Summary

Object-Oriented Programming

Object-Oriented Programming

Creating a class

Working with attributes

Working with methods

More about attributes

Class methods

Inheritance

Appending objects and classes using roles

Using introspection to learn more

Method postfix operators

Summary

Input and Output

Input and Output

Standard input and output

Working with files and directories

Reading from a stream

Writing to a stream

Summary

Working with Exceptions

Working with Exceptions

The try block

Soft failures

The CATCH phaser

The Exception object

The Failure object

Creating custom exceptions

Summary

Regexes

Regexes

Matching against regexes

Literals

Character classes

Creating repeated patterns with quantifiers

Extracting substrings with capturing

Using alternations in regexes

Positioning regexes with anchors

Looking forward and backward with assertions

Modifying regexes with adverbs

Substitution and altering strings with regexes

Summary

Grammars

Grammars

Creating a grammar

Using rules and tokens

Using actions

Using abstract syntax tree attributes

Using the actions class

The whole program

Summary

Concurrent Programming

Concurrent Programming

Junctions

Threads

Promises

Channels

Summary

Functional Programming

Functional Programming

What is functional programming?

Using recursion

Using reduction

Higher-order functions and lambdas

Piping data and feed operators

Manipulating the scope

Creating and using iterators

Lazy and infinite lists

Summary

Reactive Programming

Reactive Programming

What is reactive programming?

On-demand supplies

Live supplies

Summary

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Using alternations in regexes

Let us look once again to our naïve regex for matching phone numbers:

rx/ \+? (\d || \s || \-)+ /

Vertical bars separate different variants within the group in parentheses. It can be either \d, or \s, or \-. In the context of regexes, this is call alternation. Different variants are, correspondingly, called alternatives.

In Perl 6, there are two forms of alternation separator in regexes—single | and double || vertical bars . With a single vertical bar, the longest variant always wins. With the double bar, the first matched alternative wins.

In the phone number example, each alternative is exactly one symbol long. So, there is no difference between | and || there. In other cases, the choice of the operator may drastically change the result.

For example, take the two regexes from the following example and match the forms of an adjective...

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