Elixir Modules and Structs — Organization and Data with Types

DodaTech Updated 2026-06-29 1 min read

In this tutorial, you will learn about Elixir Modules and Structs. We cover key concepts, practical examples, and best practices to help you master this topic.

Modules in Elixir group functions together, while structs provide typed, named fields for data. Together they form the building blocks of well-organized Elixir applications.

In this tutorial, you'll learn how to structure Elixir code with modules and structs.

Modules

defmodule MyApp.Greeter do
  @moduledoc "Handles greetings"

  @default_name "World"  # Module attribute (constant)

  def hello(name \ @default_name) do
    "Hello, #{name}!"
  end
end

MyApp.Greeter.hello()         # => "Hello, World!"
MyApp.Greeter.hello("Alice")  # => "Hello, Alice!"

Structs

defmodule User do
  defstruct [:name, :age, :email]

  @type t :: %User{
    name: String.t(),
    age: non_neg_integer(),
    email: String.t()
  }

  def create(name, age, email) do
    %User{name: name, age: age, email: email}
  end

  def adult?(%User{age: age}), do: age >= 18
end

# Creating
alice = %User{name: "Alice", age: 30, email: "alice@example.com"}
alice.name  # => "Alice"

# Pattern matching on structs
%User{name: name} = alice
name  # => "Alice"

# Required fields
defmodule Config do
  @enforce_keys [:host, :port]
  defstruct [:host, :port, :protocol]
end

# %Config{port: 8080}  # Error! Missing required key :host
%Config{host: "localhost", port: 8080}  # OK

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