Appendix J: Built-In Classes and Types

ZuzuScript has a small set of built-in classes and runtime type names. They are used by typeof, instanceof, type annotations, constructors, and exception matching. The tree below follows the built-in inheritance hierarchy used by the runtime.

Any - the top type; every value matches it.
- Null - the null value.
- Boolean - true and false.
- Number - numeric values.
- String - Unicode text strings.
- BinaryString - byte strings.
- Task - asynchronous task values.
- Object - object values.
  - Collection - the abstract base for built-in collection values.
    - Array - ordered lists.
    - Set - unique unordered values.
    - Dict - string-keyed mappings.
    - PairList - ordered key/value pairs that may repeat keys.
    - Bag - counted multisets.
  - Exception - the base class for catchable exceptions.
    - TypeException - type mismatch failures.
    - AssertionException - assertion failures.
    - ExhaustedException - iterator or generator exhaustion.
    - CancelledException - cancelled asynchronous work.
      - TimeoutException - timeout cancellation.
    - ChannelClosedException - send or receive on a closed channel.
  - Pair - a key/value pair object.
  - Regexp - regular expression values.
- Function - function values.
- Trait - trait objects.
- Class - class objects.

Some standard-library modules define additional exception subclasses. These are not always present as ambient names, but they are part of the standard library when their modules are imported:

Exception
- MarshallingException - thrown by std/marshal.dump.
- UnmarshallingException - thrown by std/marshal.load.
- BailOutException - thrown by test/more bailout helpers.
- SkipAllException - thrown by test/more skip-all helpers.

typeof may also report Method for a bound method value. It is a runtime type name rather than a built-in class in the core inheritance tree.