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Programming Elixir 1.2: Functional |> Concurrent |> Pragmatic |> Fun


Cover image for Programming Elixir 1.2

Programming Elixir 1.2

Functional |> Concurrent |> Pragmatic |> Fun


You want to explore functional programming, but are put off by the academic feel (tell me about monads just one more time). You know you need concurrent applications, but also know these are almost impossible to get right. Meet Elixir, a functional, concurrent language built on the rock-solid Erlang VM. Elixir’s pragmatic syntax and built-in support for metaprogramming will make you productive and keep you interested for the long haul. This book is the introduction to Elixir for experienced programmers.

Programming Elixir 1.3 is now available.

Maybe you need something that’s closer to Ruby, but with a battle-proven environment that’s unrivaled for massive scalability, concurrency, distribution, and fault tolerance. Maybe the time is right for the Next Big Thing. Maybe it’s Elixir.

This edition of the book has been updated to cover Elixir 1.2, including the new with expression, the exrm release manager, and the removal of deprecated types.

Check out the short video on Elixir at, or the more detailed 30 minute video at

And don’t forget to download this handy cheat sheet for Elixir syntax.

About this Title

Pages: 352
Published: 2016-03-08
Release: P2.0 (2016-08-06)
ISBN: 978-1-68050-166-7

As a developer, you’ve probably heard that functional programming techniques help manage the complexities of today’s real-world, concurrent systems. You’re also investigating designs that help you maximize uptime and manage security.

This book is your guide to Elixir, a modern, functional, and concurrent programming language. Because Elixir runs on the Erlang VM, and uses the underlying Erlang/OTP architecture, it benefits from almost 20 years of research into high performance, highly parallel, and seriously robust applications. Elixir brings a lot that’s new: a modern, Ruby-like, extendable syntax, compile and runtime evaluation, a hygienic macro system, and more.

But, just as importantly, Elixir brings a sense of enjoyment to parallel, functional programming. Your applications become fun to work with, and the language encourages you to experiment.

Part 1 covers the basics of writing sequential Elixir programs. We’ll look at the language, the tools, and the conventions.

Part 2 uses these skills to start writing concurrent code—applications that use all the cores on your machine, or all the machines on your network! And we do it both with and without OTP.

And Part 3 looks at the more advanced features of the language, from DSLs and code generation to extending the syntax.

By the end of this book, you’ll understand Elixir, and know how to apply it to solve your complex, modern problems.

Read the reviews .

What You Need

You’ll need a computer, a little experience with another high-level language, and a sense of adventure. No functional programming experience is needed.

Contents & Extracts


  • Conventional Programming
    • Pattern Matching
      • Assignment: I Do Not Think It Means What You Think It Means.
      • More Complex Matches
      • Ignoring a Value with _ (Underscore)
      • Variables Bind Once (per Match)
      • Another Way of Looking at the Equals Sign
    • Immutability
      • You Already Have (Some) Immutable Data
      • Immutable Data Is Known Data
      • Performance Implications of Immutability
      • Coding with Immutable Data
    • Elixir Basics
      • Built-in Types
      • Value Types
      • System Types
      • Collection Types
      • Maps
      • Names, Source Files, Conventions, Operators, and So On
      • Variable Scope
      • End of the Basics
    • Anonymous Functions
      • Functions and Pattern Matching
      • One Function, Multiple Bodies
      • Functions Can Return Functions
      • Passing Functions As Arguments
      • Functions Are the Core
    • Modules and Named Functions
      • Compiling a Module
      • The Function’s Body Is a Block
      • Function Calls and Pattern Matching
      • Guard Clauses
      • Default Parameters
      • Private Functions
      • The Amazing Pipe Operator: |>
      • Modules
      • Module Attributes
      • Module Names: Elixir, Erlang, and Atoms
      • Calling a Function in an Erlang Library
      • Finding Libraries
    • Lists and Recursion excerpt
      • Heads and Tails
      • Using Head and Tail to Process a List
      • Using Head and Tail to Build a List
      • Creating a Map Function
      • Keeping Track of Values During Recursion
      • More Complex List Patterns
      • The List Module in Action
      • Get Friendly with Lists
    • Maps, Keyword Lists, Sets, and Structs
      • How to Choose Between Maps and Keyword Lists
      • Keyword Lists
      • Maps
      • Pattern Matching and Updating Maps
      • Updating a Map
      • Structs
      • Nested Dictionary Structures
      • Sets
      • With Great Power Comes Great Temptation
    • An Aside—What Are Types?
    • Processing Collections—Enum and Stream
      • Enum—Processing Collections
      • Streams—Lazy Enumerables
      • The Collectable Protocol
      • Comprehensions
      • Moving Past Divinity
    • Strings and Binaries
      • String Literals
      • The Name “strings”
      • Single-Quoted Strings—Lists of Character Codes
      • Binaries
      • Double-Quoted Strings Are Binaries
      • Binaries and Pattern Matching
      • Familiar Yet Strange
    • Control Flow
      • if and unless
      • cond
      • case
      • Raising Exceptions
      • Designing with Exceptions
      • Doing More with Less
    • Organizing a Project
      • The Project: Fetch Issues from GitHub
      • Task: Use Mix to Create Our New Project
      • Transformation: Parse the Command Line
      • Step: Write Some Basic Tests
      • Transformation: Fetch from GitHub
      • Task: Use Libraries
      • Transformation: Convert Response
      • Transformation: Sort Data
      • Transformation: Take First n Items
      • Transformation: Format the Table
      • Task: Make a Command-Line Executable
      • Task: Add Some Logging
      • Task: Test the Comments
      • Task: Create Project Documentation
      • Coding by Transforming Data
  • Concurrent Programming
    • Working with Multiple Processes
      • A Simple Process
      • Process Overhead
      • When Processes Die
      • Parallel Map—The “Hello, World” of Erlang
      • A Fibonacci Server
      • Agents—A Teaser
      • Thinking in Processes
    • Nodes—The Key to Distributing Services excerpt
      • Naming Nodes
      • Naming Your Processes
      • I/O, PIDs, and Nodes
      • Nodes Are the Basis of Distribution
    • OTP: Servers
      • Some OTP Definitions
      • An OTP Server
      • GenServer Callbacks
      • Naming a Process
      • Tidying Up the Interface
    • OTP: Supervisors
      • Supervisors and Workers
      • Supervisors Are the Heart of Reliability
    • OTP: Applications
      • This Is Not Your Father’s Application
      • The Application Specification File
      • Turning Our Sequence Program into an OTP Application
      • Supervision Is the Basis of Reliability
      • Releasing Your Code
      • EXRM—the Elixir Release Manager
      • OTP Is Big—Unbelievably Big
    • Tasks and Agents
      • Tasks
      • Agents
      • A Bigger Example
      • Agents and Tasks, or GenServer?
  • More-Advanced Elixir
    • Macros and Code Evaluation
      • Implementing an if Statement
      • Macros Inject Code
      • Using the Representation As Code
      • Using Bindings to Inject Values
      • Macros Are Hygienic
      • Other Ways to Run Code Fragments
      • Macros and Operators
      • Digging Deeper
      • Digging Ridiculously Deep
    • Linking Modules: Behavio(u)rs and Use
      • Behaviours
      • Use and using
      • Putting It Together—Tracing Method Calls
      • Use use
    • Protocols—Polymorphic Functions
      • Defining a Protocol
      • Implementing a Protocol
      • The Available Types
      • Protocols and Structs
      • Build-In Protocols
      • Protocols Are Polymorphism
    • More Cool Stuff
      • Writing Your Own Sigils
      • Multi-app Umbrella Projects
      • But Wait! There’s More!


Dave Thomas is a programmer who likes to evangelize cool stuff. He cowrote The Pragmatic Programmer, and was one of the creators of the Manifesto for Agile Software Development. His book Programming Ruby introduced the Ruby language to the world, and Agile Web Development with Rails helped kickstart the Rails revolution.

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