A Diagrammatic Notation for Abstract Syntax and Abstract Structured Objects

The concept of abstract syntax is commonly applied to the formal specification of programming language semantics and is also useful in the broader context of software design. This paper proposes a scheme for the representation of abstract syntax specifications in the form of easily understood charts. The structuring primitives considered are those of scalar enumeration, heterogeneous aggregation, homogeneous lists and sets, disjunction, and partial functions. Secondarily, a related system of charts for depicting particular objects with a given structure is proposed. Examples are given to illustrate the use of these diagrammatic notations in the contexts of language description and software design and documentation.