Book Image

Perl 6 Deep Dive

By : Andrew Shitov

Book Image

Perl 6 Deep Dive

By: Andrew 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

Working with Rakudo Star

Writing our Hello World program

Writing Code

Whitespaces and unspaces

Creating Pod documentation

Simple input and output

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

Working with Operators

Working with Operators

Operator classification

Operators in Perl 6

Meta-operators in Perl 6

User-defined operators

Control Flow

Understanding code blocks and variable scoping

Conditional checks

Executing code once

Collecting data with gather and take

Setting the topic with given

Subroutines

Creating and calling subroutines

Type constraints

Nested subroutines

Creating operators

Passing functions as arguments

Modules

Creating a module

Object-Oriented Programming

Object-Oriented Programming

Creating a class

Working with attributes

Working with methods

More about attributes

Appending objects and classes using roles

Using introspection to learn more

Method postfix operators

Input and Output

Input and Output

Standard input and output

Working with files and directories

Reading from a stream

Writing to a stream

Working with Exceptions

Working with Exceptions

The CATCH phaser

The Exception object

The Failure object

Creating custom exceptions

Regexes

Matching against regexes

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

Grammars

Creating a grammar

Using rules and tokens

Using abstract syntax tree attributes

Using the actions class

The whole program

Concurrent Programming

Concurrent Programming

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

Reactive Programming

Reactive Programming

What is reactive programming?

On-demand supplies

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Using reduction

In the previous section, we were calculating the sum of the numbers between 10 and 15. The program, after some transformations, became equivalent to the following one:

say 10 + (11 + (12 + (13 + (14 + 15))));

Each pair of parentheses here corresponds to the recursive call of the sum function. Calls of the function are replaced here with its implementation. This is one of the consequences of the restriction of the state-less approach. Would the function depend on the program state, it would not be possible to replace the function call with its implementation without knowing the values reflecting the state at different moments.

As parentheses do not change any order of execution here, let's remove them:

say 10 + 11 + 12 + 13 + 14 + 15;

What we see here is a list of all the values between 10 and 15 separated by the + operator. We have already met that in the...