Erlang is a programming language that was designed for building distributed, fault-tolerant, and scalable applications. Developed in the 1980s at Ericsson, it has since been used to power many high-traffic and mission-critical systems such as WhatsApp and Facebook Chat. This guide will introduce you to Erlang, show you how to write Erlang code with an example, and explain what are the best applications for it.

Introduction to Erlang

Erlang is a functional programming language that is designed to be concurrent and fault-tolerant. It is particularly well-suited for building distributed systems and telecommunications applications. Erlang was first developed in the 1980s by Joe Armstrong, Robert Virding, and Mike Williams at Ericsson, the Swedish telecommunications company. The goal was to build a language that could handle the demands of the telecommunications industry, which required high levels of reliability and fault-tolerance. Erlang was open-sourced in 1998 and has since gained a large following in the programming community.

Writing Erlang Code

To get started with Erlang, you need to have the Erlang runtime system installed on your computer. You can download the latest version of Erlang from the official website. Once you have Erlang installed, you can use a text editor such as Emacs or Vim to write and edit Erlang code.

Here is an example of a simple Erlang program that prints "Hello, world!" to the console:

```
-module(hello_world).
-export([start/0]).

start() ->
    io:format("Hello, world!~n").
```

To run this program, save it in a file called "hello_world.erl". Then, open a terminal window and navigate to the directory where you saved the file. Start the Erlang shell by typing "erl" into the terminal. Once the shell has started, compile the program by typing "c(hello_world)." and pressing Enter. Finally, run the program by typing "hello_world:start()." and pressing Enter. You should see "Hello, world!" printed to the console.

Applications of Erlang

Erlang is particularly well-suited for building distributed, fault-tolerant, and high-performance systems. Some of the most common applications of Erlang include:

1. Telecommunications: Erlang was originally developed for the telecommunications industry, and it is still widely used in this field today.

2. Web servers: Erlang's lightweight processes and concurrency model make it ideal for building high-performance web servers.

3. Messaging systems: Erlang's built-in support for message passing and concurrency make it ideal for building messaging systems such as chat applications.

4. Gaming: Erlang's low-latency and fault-tolerant capabilities make it ideal for building online gaming platforms.

Conclusion

Erlang is a powerful and versatile programming language that is well-suited for building distributed, fault-tolerant, and high-performance systems. With its lightweight processes, concurrency model, and built-in support for message passing, Erlang is particularly well-suited for building applications in the telecommunications, web server, messaging, and gaming industries. If you're looking to learn a new programming language or explore new programming paradigms, Erlang is definitely worth checking out.