Abstract data types
If you’re using data types to match or restrict values and
need more flexibility than what the core data types (such as String or Array) allow, you can use one of the abstract data types to construct a data type that suits your needs and
matches the values you want.
Each of Puppet's core data types has a corresponding value that represents that data type, which can be used to match values of that type in several contexts. Each of those core data types only match a particular set of values. They let you further restrict the values they’ll match, but only in limited ways, and there’s no way to expand the set of values they’ll match. If you need to do this, use the corresponding abstract data type.