Programming Elixir 1.2

Using Dialyzer

Dialyzer analyzes code that runs on the Erlang VM, looking for potential errors. To use it with Elixir, we have to compile our source into .beam files and make sure that the debug_info compiler option is set (which it is when running mix in the default, development mode). Let’s see how to do that by creating a trivial project with two source files.

$ mix new simple
...
$ cd simple

Inside the project, let’s create a simple function. Being lazy, I haven’t implemented the body yet.

defmodule Simple do
  @type atom_list :: list(atom)
  @spec count_atoms(atom_list)  :: non_neg_integer
  def count_atoms(list) do
    # ...
  end
end

Let’s run dialyzer on our code. Because it works from .beam files, ...