Programming Elixir 1.2

Maps

A map is a collection of key/value pairs. A map literal looks like this:

%{ key => value, key => value }

Here are some maps:

iex> states = %{ "AL" => "Alabama", "WI" => "Wisconsin" }
%{"AL" => "Alabama", "WI" => "Wisconsin"}

iex> responses = %{ { :error, :enoent } => :fatal, { :error, :busy } => :retry }
%{{:error, :busy} => :retry, {:error, :enoent} => :fatal}

iex> colors = %{ :red => 0xff0000, :green => 0x00ff00, :blue => 0x0000ff }
%{blue: 255, green: 65280, red: 16711680}

In the first case the keys are strings, in the second they’re tuples, and in the third they’re atoms. Although typically all the keys in a map are the same type, that isn’t required.

iex> %{ "one" => 1, :two ...