1.21 Map

KC3 maps are like Elixir maps, they are key-values enclosed in %{} :

ikc3> a = %{id: 1, title: "My title", message: "Hello, world !"}
%{id: 1,
  title: "My title",
  message: "Hello, world !"}

Destructuring works with maps to extract values :

ikc3> %{id: id, title: "My title", message: message} = ^ a
%{id: 1,
  title: "My title",
  message: "Hello, world !"}
ikc3> id
1
ikc3> message
"Hello, world !"

You can use the dot syntax to access map values from a Sym key :

ikc3> a = %{id: 1, title: "My title", message: "Hello, world !"}
%{id: 1,
  title: "My title",
  message: "Hello, world !"}
ikc3> a.id
1
ikc3> a.message
"Hello, world !"

The bracket syntax allows you to query any key type :

ikc3> a[:id]
1
ikc3> a[:message]
"Hello, world !"

You can also use the KC3.access function for the same result :

ikc3> a = %{id: 1, title: "My title", message: "Hello, world !"}
%{id: 1,
  title: "My title",
  message: "Hello, world !"}
ikc3> access(a, [:id])
1
ikc3> access(a, [:message])
"Hello, world !"

To update an existing map you can use Map.put like this :

ikc3> a = %{id: 1, title: "My title"}
%{id: 1,
  title: "My title"}
ikc3> a = Map.put(a, :message, "Hello, world !")
%{id: 1,
  title: "My title",
  message: "Hello, world !"}

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