. In this paper we present an implementation of action notation based on a formal and modular speci cation of its semantics. This specication allows an automatic generation of an environment consisting of an interpreter and a debugger which allows the visualization of an action notation program execution and relates it to the given formal specication. The semantic description presented here is based on Montages, which is a semi-visual formalism for the speci cation of the syntax and semantics of programming languages. The tool support for Montages, called GemMex is used to execute the action notation specication and thereby generate an environment for executing action notation programs. Moreover, the specication maintains and renes the structuring of actions in terms of facets and thus ensures that the modularity present in action notation is retained in its semantic description. 1 Introduction Action semantics [30,34,52] is a specication formalism for the semantics of program...

Action semantics is a semantic meta-language developed by Mosses and Watt for specifying programming languages. The work reported in this thesis is part of a project to develop a system, called ACTRESS, that is a semantics-directed compiler generator based on action semantics. The aims of this project are to demonstrate the suitability of action semantics for this task, and to produce a system that improves on the performance of previous semantics-directed compiler generators. Moreover the ACTRESS system aims to accept a wide range of programming languages, including dynamically-scoped and dynamically-typed languages, but not to penalise the implementations of statically-typed or statically-bound languages as a result. ACTRESS automatically generates a compiler from an action semantic description of a programming language, and has been used to generate compilers for a small declarative language and a small imperative language. The generated compiler uses a number of standard modules to...

Syntax Tree as input. The algorithm traverses the tree in a Modular SOS fashion: the traversal is directed by combinators, until a subtree can be collapsed. The tree thus decreases in depth in a bottom up fashion, while traversing it top down for each step. The main di#erence between acr and evalan is that acr employs term rewriting only to reduce combined actions. All primitive actions (including data operations and predicates) are hardcoded in C. Especially for interacting actions the performance gain is expected to be more than marginal since no matching is involved in rotating the schedule (and this is likely to occur very often).

Montages is a formalism for giving executable specications of programming languages. In contrast to related formalisms, it is state-based, and specications can be given in an imperative or object-oriented style with which most programmers are comfortable. Hence, in the context of Domain Specic Languages (DSLs), it provides a framework in which domain engineers can themselves extend and maintain their language. It also uses visual notations, resulting in concise, intelligible specications. Using the associated tool support Gem-Mex, such specications can be used to automatically generate a programming environment with animation facilities. In this paper, we give an overview of the formalism and the tool support, focusing on its advantages in DSL maintenance and implementation. Towards this we also present a case study using a language called HYSDEL, developed by control engineers for specifying hybrid systems. A full implementation of this language is available and is currently bein...