From Ruby to Elixir

Maps—Your Data Layer Foundation

Maps are the most important data type in your Elixir toolbox. A map consists of key-value pairs, where the key and value can be any data type. In practice, you’ll use maps to hold and pass around all of the data in your application.

The Basics

Maps are created with the %{} syntax. You can create an empty map or set the initial key-value pairs in the map. Try it out in IEx:

$ iex
iex> empty = %{}
%{}

iex> populated = %{key: "value", another: "entry"}
%{another: "entry", key: "value"}

iex> Map.get(populated, :another)
"entry"

iex> populated[:another]
"entry"

iex> populated.another
"entry"

You’ll notice that the second map came out in a different order ...