This definition simplifies the implementation of AnObjectVector, since it allows the base implementation of AnObjectVector to construct instances of a given object on the fly (such as when AnObjectVector.readFrom is called.
This declaration simplifies the implementation of ABinaryTree, ALinkedList and their descendants, which all contain and operate on descendants of ANode.
This type is used to represent an absolute index, which is a way of referring to the position of one item in a sequence relative to the beginning of the sequence.
This type is used to represent a relative index, which is a way of referring to the position of one item in a sequence relative to another item in the sequence.