Daniel P. Friedman

A simple programming language “extension,” Graspe, for processing directed graphs is defined. Graspe consists of a type of directed graph data structure and a set of primitive operations for manipulating these structures. Graspe may be most easily implemented by embedding it in a host language. Emphasis is placed both on Graspe itself and on its method of definition. Commonly, the definition of a language involves definition of the syntactic elements and explanation of the meaning to be assigned them (the semantics). The definition of Graspe here is solely in terms of its semantics; that is, the data structures and operations are defined precisely but without assignment of a particular syntactic representation. Only when the language is implemented is assignment of an explicit syntax necessary. An example of an implementation of Graspe embedded in Lisp is given as an illustration. The advantages and disadvantages of the definition of a language in terms of its semantics are discussed.