Maps

person = %{ "name" => "Brooke", "age" => 42}

Reading Maps With Map.fetch and Map.fetch!

The Map module from Elixer’s standard offers a set of functions for working with maps.

{:ok, "Brooke"} Map.fetch(person, "name")

• It returns a tuple when key is present.

And the :error atom when it is not.

:Map.fetch(person, "banana") // returns :error atom

Map.fetch!(person, "name") // returns the person name if present.

and raises an Keyerror exception if the person is not present.

Reading Maps with pattern Matching

person = %{"name" => "Brooke", "age" => 42}
%{ "name" => name, "age" => age } = person
IO.puts name

We can pattern match only the portion that we are interested in.

person = %{"name" => "Brooke", "age" => 42}
%{"name" => name} = person
IO.puts name


person = %{ "name" => "Brooke",
            "address" => %{ "city" => "Orlando",
                            "state" => "FL" }}


%{ "address" => %{ "state" => state }} = person

IO.puts "State: #{state}"