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)

What is functional programming?

Functional programming is the way of computing using a series of functions. Functions are understood here in the mathematical sense, not in the sense of subroutines in Perl 6. A very important principle of functional programming is that functions must have no side effects. In particular, that means that variables must be immutable—assigning a new value is forbidden.

All the topics that we will discuss in this chapter are the consequences of the preceding restrictions. It is important to realize that, for example, lambda functions are not the core essence of functional programming but are just one of the ways of following the main principle of having no side effects, such is changing some global variables that affect the result of the function.

Let us take a function f($x) and call it twice with the same argument. Will the second call return...