List processing primitives for BASIC

Abstract

This paper describes list-processing primitives which form a component of an interactive graphics system. This system, developed at Bowling Green State University, has a plasma display panel as its central component. This system comprises a BASIC interpreter to which has been added a rich variety of graphic and list-processing primitives. These are implemented as additional BASIC verbs. The list-processing primitives permit creation of arbitrarily complex list structures: trees, multiply linked lists, etc. can all be constructed. It is possible to manipulate list and node names in a natural way. Lists, sublists, and nodes can be added and deleted, lists can be searched, and the list space dynamically reformatted if desired. The system also includes an extremely flexible mechanism for describing and manipulating data contained in a node. Several data types are available ranging from floating point to variable-length integer. It is possible to manipulate data at the bit level. This facility greatly increases the flexibility of the graphic system since it is possible to represent structural relationships between the components of a figure. © 1975.