Programmer Passport: Elixir

Maps

Maps are key-value pairs, but they’re built for fast random access. That means you can access any key quickly. In big O notation,^[10] the operation is O(Log n) for an n-item map.

Map Syntax, Sugar, and Access

Let’s build a map from a list of tuples. In your console, make sure you still have the Keyword called numbers defined. Then, create a new map with Map.new, like this:

iex> numbers = [one: 1, two: 2, three: 3]
[one: 1, two: 2, three: 3]
iex> numbers_map = Map.new(numbers)
%{one: 1, three: 3, two: 2}

That’s straightforward. The syntax of a map is the same as when the keys are atoms. Maps have a leading % and curly braces surrounding the keys and values. If keys are first, you can use the shorthand atom syntax.

If you don’t ...