66 lines
2.7 KiB
Elixir
66 lines
2.7 KiB
Elixir
defmodule Maps do
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use Koans
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koan "Maps represent structured data, like a person" do
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assert %{ :name => "Jon",
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:last_name => "Snow",
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:age => 27 } == %{ :name => "Jon",
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:last_name => "Snow",
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:age => 27 }
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end
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koan "You can get all the keys from the map" do
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assert Map.keys(%{ :name => "Jon", :last_name => "Snow", :age => 27 }) == [:age, :last_name, :name]
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end
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koan "Or you can also get all the values from it" do
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assert Map.values(%{ :name => "Jon", :last_name => "Snow", :age => 27 }) == [27, "Snow", "Jon"]
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end
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koan "Fetching a value returns a touple with ok when it exists..." do
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assert Map.fetch(%{ :name => "Jon", :last_name => "Snow", :age => 27 }, :age) == {:ok, 27}
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end
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koan "...or the atom :error when it doesnt." do
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assert Map.fetch(%{ :name => "Jon", :last_name => "Snow", :age => 27 }, :family) == :error
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end
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koan "Extending a map is a simple as put'ing in a new pair" do
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assert Map.put(%{ :name => "Jon", :last_name => "Snow"}, :age, 27) == %{ :name => "Jon", :last_name => "Snow", :age => 27 }
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end
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koan "Put can also overwrite existing values" do
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assert Map.put(%{ :name => "Jon", :last_name => "Snow", :age => 15}, :age, 27) == %{ :name => "Jon", :last_name => "Snow", :age => 27 }
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end
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koan "Or you can use some syntactic sugar for exiting elements." do
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initial = %{ :name => "Jon", :last_name => "Snow", :age => 15}
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assert %{ initial | :age => 27 } == %{ :name => "Jon", :last_name => "Snow", :age => 27 }
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end
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koan "Can remove pairs by key" do
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assert Map.delete(%{ :name => "Jon", :last_name => "Snow", :age => 15}, :age) == %{ :name => "Jon", :last_name => "Snow"}
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end
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koan "If you have a list of pairs, you can turn them into a map" do
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assert Map.new( [{:name, "Jon"}, {:last_name, "Snow"}, {:age, 27}] ) == %{ :name => "Jon", :last_name => "Snow", :age => 27 }
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end
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koan "Going back to a list of pairs is just as easy." do
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assert Map.to_list(%{ :name => "Jon", :last_name => "Snow", :age => 27 }) == [age: 27, last_name: "Snow", name: "Jon" ]
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end
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koan "Can merge maps" do
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assert Map.merge(%{:name => "Jon"}, %{ :last_name => "Snow"}) == %{:name => "Jon", :last_name => "Snow"}
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end
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koan "When merging, the last map wins" do
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assert Map.merge(%{:name => "Robert", :last_name => "Snow"}, %{ :last_name => "Baratheon"}) == %{:name => "Robert", :last_name => "Baratheon"}
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end
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koan "You can also select sub-maps out of a larger map" do
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initial = %{ :name => "Jon", :last_name => "Snow", :age => 15}
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assert Map.take(initial, [:name, :last_name]) == %{ :name => "Jon", :last_name => "Snow"}
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end
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end
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