Mastering the Art of Programming in Elixir/

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Modules

Modules

Understand nested modules and different kinds of directives in Elixir.

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Modules provide namespaces for things we define. They also act as wrappers for macros, structs, protocols, and other modules. If we want to reference a function defined in a module from outside that module, we need to prefix the reference with the module’s name. We don’t need that prefix if code references something inside the same module as itself, as in the below example.

Run the Mod.func1 or Mod.func2 commands in the terminal below. Don’t forget to start an iex session first with the iex -S mix command.

defmodule First.MixProject do
  use Mix.Project

  def project do
    [
      app: :first,
      version: "0.1.0",
      elixir: "~> 1.12",
      start_permanent: Mix.env() == :prod,
      deps: deps()
    ]
  end

  # Run "mix help compile.app" to learn about applications.
  def application do
    [
      extra_applications: [:logger]
    ]
  end

  # Run "mix help deps" to learn about dependencies.
  defp deps do
    [
      # {:dep_from_hexpm, "~> 0.3.0"},
      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
    ]
  end

  def hello do
    [
    IO.puts("Hello")
    ]
  end
end
Modules in Elixir

The func2 function can call func1 directly because it’s inside the same module (line 5). Outside the module, we have to use the fully qualified name—for example, Mod.func1 and Mod.func2 at lines 10 and 11, ...