GLOSS: A semantic model of programming languages

GLOSS is a machine and language for modeling the semantics of programming languages. GLOSS is not intended to be a tool for mathematical proofs. Instead it is intended to provide an easily read graphical notation in which programming language structures and transformations (operators) can be specified. Johnston's Contour Model [Jl] has a similar intention, but GLOSS has a more flexible structure. Because the human eye can perceive a graphical notation more readily than a mathematical or programmatical notation, GLOSS and Johnston's Contour Model are more elucidating than the Vienna Definition Language [L1]. GLOSS has seven primitive objects: integer objects, bit string objects, character string objects, reference objects, vector objects, record objects, and constructor objects. Integers, bit strings, character strings, and references have their usual meanings. A vector is an ordered set of objects indexed from zero. A record is an unordered set of two tuples, each of whose first component is an identifier (character string) and whose second component is an object. The identifier is used to select its associated object. All of the above objects have a type such as integer, bit string, etc. and a value which is the object itself. A constructor object permits the formation of a new type of object.