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)

Anonymous subs

A subroutine without a name is called an anonymous sub. You cannot call it by name, but it is still possible to run it via a handle, which, for example, is stored in a variable. All the attributes of a regular sub, such as a signature and a body, are defined in the same way as the normal subs.

In the following code, we will create an anonymous sub and save it in the $add variable; a space before the signature is required:

my $add = sub ($x, $y) {$x + $y}
say $add(10, 20); # 30

Perl 6 allows a mixture of regular and anonymous subs. The anon keyword creates an anonymous sub out of the regular one, so its name can still be used to call it. First, look at the sub, which can be used both as an anonymous one and be called by its name:

my $add = sub add ($x, $y) {$x + $y}
say $add(1, 2); # using anonymous sub
say add(3, 4);  # using regular sub call by name

Now, let us...