That’s what it takes to write an Hello World program in Erlang, after you installed the Erlang system on your machine.

Here’s the program itself:

What does that means? Briefly:

-module(hello).

Create a module for the following functions, think of it like a namespace declaration.

-export([hello_world/0]).

This tells the compiler that we want to export the

hello_world/0

function to the outer world. It means the other modules can call this function. What does the “/0″ means? It means the “hello_world” function with 0 parameters. In Erlang, you can have different functions with the same name and different number of parameters.

hello_world()->

Declare a new function named “hello_world” that accept no parameters, the body will follow the arrow.

    io:format(“Hello World ~n”).

This calls the “format” function from the module “io” that prints out the Hello World message. The “~n” characters prints the Carriage Return, the same as “/n” in other languages.

To run your program you must start the Erlang shell first:

Try it, and understand it. Next time will be a little bit more complex!

Note: if you guess why by copying and pasting the code you get a lot of errors, that’s because SciTe, the editor I use, exports the code with fancy double quotes. That’s a good reason to not being lazy and write the program by yourself! Writing it’s a nice way of learning!