Formal Component-Based Semantics

One of the proposed solutions for improving the scalability of semantics of programming languages is Component-Based Semantics, introduced by Peter D. Mosses. It is expected that this framework can also be used effectively for modular meta theoretic reasoning. This paper presents a formalization of Component-Based Semantics in the theorem prover Coq. It is based on Modular SOS, a variant of SOS, and makes essential use of dependent types, while profiting from type classes. This formalization constitutes a contribution towards modular meta theoretic formalizations in theorem provers. As a small example, a modular proof of determinism of a mini-language is developed.Comment: In Proceedings SOS 2011, arXiv:1108.279

Logical Specification of Operational Semantics

Various logic-based frameworks have been proposed for specifying the operational semantics of programming languages and concurrent systems, including inference systems in the styles advocated byPlotkin and by Kahn, Horn logic, equational specifications, reductionsystems for evaluation contexts, rewriting logic, and tile logic.We consider the relationship between these frameworks, and assess theirrespective merits and drawbacks - especially with regard to the modularity of specifications, which is a crucial feature for scaling up to practicalapplications. We also report on recent work towards the use of the Maudesystem (which provides an efficient implementation of rewriting logic) asa meta-tool for operational semantics

Foundations of Modular SOS

A novel form of labelled transition system is proposed, wherethe labels are the arrows of a category, and adjacent labels in computations are required to be composable. Such transition systems provide thefoundations for modular SOS descriptions of programming languages.Three fundamental ways of transforming label categories, analogous tomonad transformers, are provided, and it is shown that their applicationspreserve computations in modular SOS. The approach is illustrated withfragments taken from a modular SOS for ML concurrency primitives

A formal support to business and architectural design for service-oriented systems

Architectural Design Rewriting (ADR) is an approach for the design of software architectures developed within Sensoria by reconciling graph transformation and process calculi techniques. The key feature that makes ADR a suitable and expressive framework is the algebraic handling of structured graphs, which improves the support for specification, analysis and verification of service-oriented architectures and applications. We show how ADR is used as a formal ground for high-level modelling languages and approaches developed within Sensoria

Executable component-based semantics

The potential benefits of formal semantics are well known. However, a substantial amount of work is required to produce a complete and accurate formal semantics for a major language; and when the language evolves, large-scale revision of the semantics may be needed to reflect the changes. The investment of effort needed to produce an initial definition, and subsequently to revise it, has discouraged language developers from using formal semantics. Consequently, many major programming languages (and most domain-specific languages) do not yet have formal semantic definitions.To improve the practicality of formal semantic definitions, the PLanCompS project has developed a component-based approach. In this approach, the semantics of a language is defined by translating its constructs (compositionally) to combinations of so-called fundamental constructs, or ‘funcons’. Each funcon is defined using a modular variant of Structural Operational Semantics, and forms a language-independent component that can be reused in definitions of different languages. A substantial library of funcons has been developed and tested in several case studies. Crucially, the definition of each funcon is fixed, and does not need changing when new funcons are added to the library.For specifying component-based semantics, we have designed and implemented a meta-language called CBS. It includes specification of abstract syntax, of its translation to funcons, and of the funcons themselves. Development of CBS specifications is supported by an integrated development environment. The accuracy of a language definition can be tested by executing the specified translation on programs written in the defined language, and then executing the resulting funcon terms using an interpreter generated from the CBS definitions of the funcons. This paper gives an introduction to CBS, illustrates its use, and presents the various tools involved in our implementation of CBS

Maude Object-Oriented Action Tool

MAIDL, André Murbach; CARVILHE, Claudio; MUSICANTE, Martin A. Maude Object-Oriented Action Tool. Electronic Notes in Theoretical Computer Science. [S.l:s.n], 2008.Object-Oriented Action Semantics (OOAS) incorporates object-oriented concepts to the Action Semantics formalism. Its main goal is to obtain more readable and reusable semantics specifications. Moreover, it supports syntax-independent specifications, due to the way classes are written. Maude Object-Oriented Action Tool (MOOAT) is an executable environment for Object-Oriented Action Semantics implemented as a conservative extension of Full Maude and Maude MSOS Tool (MMT). The Modular SOS of Action Notation has been implemented using MMT transitions and Full Maude has been used to implement the Classes Notation. The syntax created by MOOAT is fairly similar to the original Object-Oriented Action Semantics syntax. In addition to it, the tool combines the modularity aspects observed in the object-oriented approach with the efficient execution and analysis of the Maude system. We use MOOAT to describe syntaxindependent specifications of programming languages. In this way, we show how Constructive Object-Oriented Action Semantics (COOAS) may be achieved as a combination between Object-Oriented Action Semantics and Constructive Action Semantics (CAS) using MOOAT, in order to increase the modularity aspects observed in the object-oriented formalism. This paper reports on the development of Maude Object-Oriented Action Tool and its application to the formal specification of programming languages

Exploiting Labels in Structural Operational Semantics

Structural Operational Semantics (SOS) allows transitions to be labelled. This is fully exploited in SOS descriptions of concurrent systems, but usually not at all in conventional descriptions of sequential programming languages. This paper shows how the use of labels can provide significantly simpler and more modular descriptions of programming languages. However, the full power of labels is obtained only when the set of labels is made into a category, as in the recently-proposed MSOS variant of SOS

Pragmatics of Modular SOS

Modular SOS is a recently-developed variant of Plotkin's Structural Operational Semantics (SOS) framework. It has several pragmatic advantages over the original framework--the most significant being that rules specifying the semantics of individual language constructs can be given definitively, once and for all. Modular SOS is being used for teaching operational semantics at the undergraduate level. For this purpose, the meta-notation for modular SOS rules has been made more user-friendly, and derivation of computations according to the rules is simulated using Prolog. After giving an overview of the foundations of Modular SOS, this paper gives some illustrative examples of the use of the framework, and discusses various pragmatic aspects

Rewriting Logic Semantics of a Plan Execution Language

The Plan Execution Interchange Language (PLEXIL) is a synchronous language developed by NASA to support autonomous spacecraft operations. In this paper, we propose a rewriting logic semantics of PLEXIL in Maude, a high-performance logical engine. The rewriting logic semantics is by itself a formal interpreter of the language and can be used as a semantic benchmark for the implementation of PLEXIL executives. The implementation in Maude has the additional benefit of making available to PLEXIL designers and developers all the formal analysis and verification tools provided by Maude. The formalization of the PLEXIL semantics in rewriting logic poses an interesting challenge due to the synchronous nature of the language and the prioritized rules defining its semantics. To overcome this difficulty, we propose a general procedure for simulating synchronous set relations in rewriting logic that is sound and, for deterministic relations, complete. We also report on two issues at the design level of the original PLEXIL semantics that were identified with the help of the executable specification in Maude