edf50fdf80
- Run mix credo --all to identify possible code optimizations - Resolve most of the errors generated by credo such as: - Numbers larger than 9999 should be written with underscores: 58_127 - Modules should have a @moduledoc tag - Comparison will always return true
58 lines
1.5 KiB
Elixir
58 lines
1.5 KiB
Elixir
defmodule Maps do
|
|
@moduledoc false
|
|
use Koans
|
|
|
|
@intro "Maps"
|
|
|
|
@person %{
|
|
first_name: "Jon",
|
|
last_name: "Snow",
|
|
age: 27
|
|
}
|
|
|
|
koan "Maps represent structured data, like a person" do
|
|
assert @person == %{first_name: ___, last_name: "Snow", age: 27}
|
|
end
|
|
|
|
koan "Fetching a value returns a tuple with ok when it exists" do
|
|
assert Map.fetch(@person, :age) == ___
|
|
end
|
|
|
|
koan "Or the atom :error when it doesn't" do
|
|
assert Map.fetch(@person, :family) == ___
|
|
end
|
|
|
|
koan "Extending a map is as simple as adding a new pair" do
|
|
person_with_hobby = Map.put(@person, :hobby, "Kayaking")
|
|
assert Map.fetch(person_with_hobby, :hobby) == ___
|
|
end
|
|
|
|
koan "Put can also overwrite existing values" do
|
|
older_person = Map.put(@person, :age, 37)
|
|
assert Map.fetch(older_person, :age) == ___
|
|
end
|
|
|
|
koan "Or you can use some syntactic sugar for existing elements" do
|
|
younger_person = %{@person | age: 16}
|
|
assert Map.fetch(younger_person, :age) == ___
|
|
end
|
|
|
|
koan "Can remove pairs by key" do
|
|
without_age = Map.delete(@person, :age)
|
|
assert Map.has_key?(without_age, :age) == ___
|
|
end
|
|
|
|
koan "Can merge maps" do
|
|
assert Map.merge(%{first_name: "Jon"}, %{last_name: "Snow"}) == ___
|
|
end
|
|
|
|
koan "When merging, the last map wins" do
|
|
merged = Map.merge(@person, %{last_name: "Baratheon"})
|
|
assert Map.fetch(merged, :last_name) == ___
|
|
end
|
|
|
|
koan "You can also select sub-maps out of a larger map" do
|
|
assert Map.take(@person, [:first_name, :last_name]) == ___
|
|
end
|
|
end
|