Creating a simple application_Elixir Cookbook-QQ阅读都市男生网

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Creating a simple application

In this recipe, we will be using Mix to create a new application.

How to do it…

To create a new Elixir application, follow these steps:

In a command-line session, enter mix help to see a list of available tasks:
```
> mix help
```
Here is what the screen will look like:
To generate a new application, type mix new simple_app:
```
> mix new simple_app
```
What happens next is shown in the following screenshot:

Inside the simple_app directory, the generated application is ready to be started. Run iex –S mix to start the application and verify that everything is working:

> iex -S mix
Erlang/OTP 17 [erts-6.1] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]
Interactive Elixir (0.15.1) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)>

Nothing happened. So is it working? The absence of messages in the IEx session is a good thing. This generated application behaves more like a library; there's no main function like in Java or C. To be sure that the application is responding, edit the lib/simple_app.ex file by inserting the following code:
```
defmodule SimpleApp do
  def greet do
    IO.puts "Hello from Simple App!"
  end
end
```
Restart the application by pressing Ctrl + C twice and entering iex –S mix again.
In the IEx session, enter SimpleApp.greet.

You will see the following output from the application:

iex(1)> SimpleApp.greet
Hello from Simple App!
:ok
iex(2)>

The Elixir application is ready to be used either on your local machine or, if a node is started, it could even be used from another machine.

How it works…

The Elixir installation provides a command-line tool called Mix. Mix is a build tool. With this tool, it is possible to invoke several tasks to create applications, manage their dependencies, run them, and more.

Mix even allows the creation of custom tasks.