(PROGRES) A very high level language based on graph grammars, developed by Andy Scheurr <[email protected]> and Albert Zuendorf <[email protected]> of RWTH, Aachen in 1991.

PROGRES supports structurally object-oriented specification of attributed graph structures with multiple inheritance hierarchies and types of types (for parametric polymorphism). It also supports declarative/relational specification of derived attributes, node sets, binary relationships (directed edges) and Boolean constraints, rule-oriented/visual specification of parameterised graph rewrite rules with complex application conditions, nondeterministic and imperative programming of composite graph transformations (with built-in backtracking and cancelling arbitrary sequences of failing graph modifications).

It is used for implementing abstract data types with graph-like internal structure, as a visual language for the graph-oriented database GRAS, and as a rule-oriented language for prototyping nondeterministically specified data/rule base transformations.

PROGRES has a formally defined semantics based on "PROgrammed Graph Rewriting Systems". It is an almost statically typed language which additionally offers "down casting" operators for run time checked type casting/conversion (in order to avoid severe restrictions concerning the language's expressiveness).

Version RWTH 5.10 includes an integrated environment.

[A. Scheurr, "Introduction to PROGRES, an Attribute Graph Grammar Based Specification Language", in Proc WG89 Workshop on Graphtheoretic Concepts in Computer Science", LNCS 411, Springer 1991].

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