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Elixir Cookbook

Elixir Cookbook

By : Paulo Pereira
4.5 (2)
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Elixir Cookbook

Elixir Cookbook

4.5 (2)
By: Paulo Pereira

Overview of this book

This book is intended for users with some knowledge of the Elixir language syntax and basic data types/structures. Although this is a cookbook and no sequential reading is required, the book’s structure will allow less advanced users who follow it to be gradually exposed to some of Elixir’s features and concepts specific to functional programming. To get the most out of this book, you need to be well versed with Erlang.
Table of Contents (11 chapters)
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Preface
Preface
What this book covers
What you need for this book
Who this book is for
Sections
Conventions
Reader feedback
Customer support
Free Chapter
1
1. Command Line
1. Command Line
Introduction
Using the terminal to prototype and test ideas
Loading and compiling modules
Getting help and accessing documentation within IEx
Using Erlang from Elixir
Inspecting your system in IEx
Inspecting your system with Observer
Creating a simple application
Managing dependencies
Generating a supervised application
Generating umbrella applications
Managing application configuration
Creating custom Mix tasks
2
2. Data Types and Structures
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2. Data Types and Structures
Understanding immutability
Adding and subtracting lists
Combining tuples into a list
Creating and manipulating keyword lists
Using pattern matching
Pattern matching an HTTPoison response
Creating a key/value store with a map
Mapping and reducing enumerables
Generating lazy (even infinite) sequences
Streaming a file as a resource
3
3. Strings and Binaries
3. Strings and Binaries
Introduction
Joining strings
Splitting strings
Replacing string codepoints with patterns
Slicing strings with ranges
Using regular expressions
Combining operations with the |> operator
Creating a word list
Determining the word frequency in a text
Reading and writing metadata from MP3 files
4
4. Modules and Functions
4. Modules and Functions
Introduction
Namespacing modules
Using module attributes as constants
Enforcing behaviors
Documenting modules
Using module directives
Using a module in the scripted mode
Defining functions with default arguments
Using guard clauses and pattern matching in function definitions
5
5. Processes and Nodes
5. Processes and Nodes
Introduction
Sending messages between processes
Making code run on all available CPUs
Using tasks to perform multiple concurrent computations
Creating a stateful server process (messages with counters)
Using agents as an abstraction around states
Using an ETS table to share the state
Creating named nodes
Connecting nodes
Executing code in a different node
6
6. OTP – Open Telecom Platform
6. OTP – Open Telecom Platform
Introduction
Implementing a GenServer
Expanding our server
Creating a supervisor
Using Observer to inspect supervisors and processes
Handling errors and managing exceptions
Packaging and releasing an OTP application
Deploying applications and updating a running system
7
7. Cowboy and Phoenix
7. Cowboy and Phoenix
Introduction
Setting up Cowboy
Serving static files
Implementing a websocket handler
Creating a Phoenix application
Defining routes
Creating a controller
Creating views and templates
Implementing topics
Protecting the Phoenix app with SSL
8
8. Interactions
8. Interactions
Introduction
Using Redis and Postgres
Using OS commands from within Elixir
Getting Twitter data
9
A. Installation and Further Reading
A. Installation and Further Reading
Installing Elixir
Installing PostgreSQL
Installing Redis
Some useful links
10
Index
Index

Understanding immutability

In Elixir, data, once created, is immutable. Whenever some input is passed into a function to be transformed, the original value remains unchanged and a new value is created.

This allows for safe concurrent access to the same data by n processes. It makes concurrency easier to manage, as it is guaranteed that no process can change the original data. Any transformation on the original data will result in new data being created.

Getting ready

To get started, we need to follow these steps:

  1. Create a file, which is transformator.ex, defining the Transformator module by adding the following code:

    defmodule Transformator do
  @default_list [1,2,3,4,5,6]

  def get_odd_numbers(list \\ @default_list) do
    Enum.filter(list, fn(x)-> rem(x,2) == 1 end)
  end

  def get_even_numbers(list \\ @default_list) do
    Enum.filter(list, fn(x)-> rem(x,2) == 0 end)
  end
end

    Note

    We define @default_list and use it in both functions preceded by \\. This means that, if no argument is...

End of Section 8
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