Book Image

Learning Elixir

By : Kenny Ballou, Kenneth Ballou
Book Image

Learning Elixir

By: Kenny Ballou, Kenneth Ballou

Overview of this book

Elixir, based on Erlang’s virtual machine and ecosystem, makes it easier to achieve scalability, concurrency, fault tolerance, and high availability goals that are pursued by developers using any programming language or programming paradigm. Elixir is a modern programming language that utilizes the benefits offered by Erlang VM without really incorporating the complex syntaxes of Erlang. Learning to program using Elixir will teach many things that are very beneficial to programming as a craft, even if at the end of the day, the programmer isn't using Elixir. This book will teach you concepts and principles important to any complex, scalable, and resilient application. Mostly, applications are historically difficult to reason about, but using the concepts in this book, they will become easy and enjoyable. It will teach you the functional programing ropes, to enable them to create better and more scalable applications, and you will explore how Elixir can help you achieve new programming heights. You will also glean a firm understanding of basics of OTP and the available generic, provided functionality for creating resilient complex systems. Furthermore, you will learn the basics of metaprogramming: modifying and extending Elixir to suite your needs.
Table of Contents (16 chapters)
Learning Elixir
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Invariable variables and pattern matching


One of the most misunderstood concepts in functional programming is that of assignment. Or, said another way, assignment doesn't exist.

Let's try to dispel this misconceived idea. In iex, we might see some code like this:

iex(1)> a = 2
2
iex(2)> a + 4
6

We may be tempted to explain the preceding code snippet with something like, "So we assign 2 to a and then add 4 to a giving us 6." However, in Elixir, this is incorrect. Elixir does not define = as an assignment operator, but rather a match operator. That is, Elixir attempts to match the left side of the = operator to that of the right.

In step 1, for Elixir to make the match succeed, we bind the value of 2 to the variable, a. Then later, when we perform the addition, we are substituting 2 for a, yielding an expression that looks like 2 + 4, which obviously equals 6.

This is a really different way to think about what is going on internally. Take a moment to let it sink in.

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