Building functional projects

We have a lot in our proverbial tool belt so far and we are adding more. Let's take a look at some more examples where we solve some relatively simple problems using Elixir. This time, however, let's use mix as well.

Flatten

We will start small, by creating a function to flatten arbitrarily deep, nested lists.

Let's create a project for it using mix new flatten:

$ mix new reverse
* creating README.md
* creating .gitignore
* creating mix.exs
* creating config
* creating config/config.exs
* creating lib
* creating lib/flatten.ex
* creating test
* creating test/test_helper.exs
* creating test/flatten_test.exs

Your mix project was created successfully.
You can use mix to compile it, test it, and more:

    cd flatten
    mix test

Run mix help for more commands.

Now, in the lib/flatten.ex file, let's create the flatten function.

Open the file in your favorite editor and add the following flatten/1 function:

defmodule Flatten do
  def flatten([]), do: []
  def flatten...