00eb17014a
While doing this, I also discovered that there is also a reference to lists in numbers, but that might a bit easier for someone to grasp, given the hint that the koan gives, and the output they see when they run it.
60 lines
1.6 KiB
Elixir
60 lines
1.6 KiB
Elixir
defmodule Maps do
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use Koans
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@intro "Maps"
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@person %{
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first_name: "Jon",
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last_name: "Snow",
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age: 27,
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}
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koan "Maps represent structured data, like a person" do
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assert @person == %{first_name: ___,
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last_name: "Snow",
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age: 27 }
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end
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koan "Fetching a value returns a tuple with ok when it exists" do
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assert Map.fetch(@person, :age) == ___
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end
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koan "Or the atom :error when it doesn't" do
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assert Map.fetch(@person, :family) == ___
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end
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koan "Extending a map is as simple as adding a new pair" do
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person_with_hobby = Map.put(@person, :hobby, "Kayaking")
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assert Map.fetch(person_with_hobby, :hobby) == ___
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end
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koan "Put can also overwrite existing values" do
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older_person = Map.put(@person, :age, 37)
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assert Map.fetch(older_person, :age) == ___
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end
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koan "Or you can use some syntactic sugar for existing elements" do
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younger_person = %{@person | age: 16}
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assert Map.fetch(younger_person, :age) == ___
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end
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koan "Can remove pairs by key" do
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without_age = Map.delete(@person, :age)
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assert Map.has_key?(without_age, :age) == ___
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end
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koan "Can merge maps" do
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assert Map.merge(%{first_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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merged = Map.merge(@person, %{last_name: "Baratheon"})
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assert Map.fetch(merged, :last_name) == ___
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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 = %{first_name: "Jon", last_name: "Snow", age: 15}
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assert Map.take(initial, [:first_name, :last_name]) == ___
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end
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end
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