Conference article

Abstract Syntax Can Make the Definition of Modelica Less Abstract.

David Broman
Department of Computer and Information Science, LinkÄoping University, Sweden

Peter Fritzon
Department of Computer and Information Science, LinkÄoping University, Sweden

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Published in: Proceedings of the 1st International Workshop on Equation-Based Object-Oriented Languages and Tools

Linköping Electronic Conference Proceedings 24:10, p. 111–126

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Published: 2007-07-18

ISBN: 978-91-7519-822-4

ISSN: 1650-3686 (print), 1650-3740 (online)


Modelica is an open standardized language used for modeling and simulation of complex physical systems. The language speci cation defines a formal concrete syntax; but the semantics is informally described using natural language. The latter makes the language hard to interpret; maintain and reason about; which affect both tool development and language evolution. Even if a completely formal semantics of the Modelica language can be seen as a natural goal; it is a well- known fact that defining understandable and concise formal semantics specifications for large and complex languages is a very hard problem. In this paper; we will discuss different aspects of formulating a Modelica specification; both in terms of what should be specified and how it can be done. Moreover; we will further argue that a "middle-way" strategy can make the specification both clearer and easier to reason about. A proposal is outlined; where the current informally specified semantics is complemented with several context-sensitive grammars; specifying intermediate representations of abstract syntax. We believe that this kind of evolutionary strategy is easier to gain acceptance for; and is more realistic in the short-term; than a revolutionary approach of using a fullyformal semantics definition of the language.


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