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

When patterns aren't enough for matching


So far, we have seen pattern matching very basically in our functions and assignment (reading binding) expressions. However, there's more that can be done when doing pattern matches, particularly when defining functions. When a simple type decomposition pattern isn't enough, we can use guards to add an extra layer to our matches.

Guards are simply boolean expressions we can add to our function definitions to make the pattern matches that we define more strict or specific.

Here are some basic examples:

iex(1)> defmodule MyMath do
...(1)> def sqrt(x) when x >= 0, do: #implement sqrt
...(1)> end

However, we are only allowed a limited set of expressions. The following is a pretty exhaustive list of the available expressions allowed in guard clauses:

  • All comparison operators (==, !=, ===, !==, >, <, <=, >=)

  • Boolean operators (and, or) and negation operators (not, !)

  • <> and ++ as long as the left side is a literal

  • The in operator...