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.
Table of Contents (15 chapters)

Creating and calling subroutines

The sub keyword creates a subroutine. A typical subroutine has a name, a list of formal parameters, and a body. However, both the name and the parameter list are optional. In Chapter 1, What is Perl 6?, we already created a subroutine to add two numbers. Let's recall it here:

sub add($x, $y) {
    return $x + $y;
}

Here, add is the name, which will later be used to call a sub. It is followed by a list of the sub's parameters—($x, $y). The body of the subroutine is enclosed inside a pair of curly braces—{return $x + $y;}.

To call a subroutine, use the name again and pass the actual parameters in parentheses:

my $a = 17;
my $b = 71;
my $sum = add($a, $b);
say "Sum of $a and $b is $sum"; # Sum of 17 and 71 is 88

There are two ways a sub can return a value. The first we just saw in the add function. It uses an explicit...