Pattern Matching and Updating Maps

The question we most often ask of our maps is, “Do you have the following keys (and maybe values)?” For example, let’s use this map: person = %{ name: "Dave", height: 1.88 }.

• Is there an entry with the key :name?

   iex> %{ name: a_name } = person 
   %{height: 1.88, name: "Dave"} 
   iex> a_name
   "Dave"

• Are there entries for the keys :name and :height?

   iex> %{ name: _, height: _ } = person
   %{height: 1.88, name: "Dave"}

• Does the entry with key :name have the value "Dave"?

   iex> %{ name: "Dave" } = person
   %{height: 1.88, name: "Dave"}

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