9. Collections

This section describes the design of the classes of aggregate data structures (collections). In addition to the concrete classes provided by the Dylan language, the heterarchy for collection classes contains several abstract classes, each of which embodies some particular behavior, usually expressed as a protocol of generic functions. Every subclass of an abstract class implements every generic function of the corresponding protocol.

The following diagram shows the collection class heterarchy. Abstract classes are shown in italic and sealed classes are shown in bold.