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

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

Meta SOS - A Maude Based SOS Meta-Theory Framework

Meta SOS is a software framework designed to integrate the results from the meta-theory of structural operational semantics (SOS). These results include deriving semantic properties of language constructs just by syntactically analyzing their rule-based definition, as well as automatically deriving sound and ground-complete axiomatizations for languages, when considering a notion of behavioural equivalence. This paper describes the Meta SOS framework by blending aspects from the meta-theory of SOS, details on their implementation in Maude, and running examples.Comment: In Proceedings EXPRESS/SOS 2013, arXiv:1307.690

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

Basic completion strategies as another application of the Maude strategy language

The two levels of data and actions on those data provided by the separation between equations and rules in rewriting logic are completed by a third level of strategies to control the application of those actions. This level is implemented on top of Maude as a strategy language, which has been successfully used in a wide range of applications. First we summarize the Maude strategy language design and review some of its applications; then, we describe a new case study, namely the description of completion procedures as transition rules + control, as proposed by Lescanne.Comment: In Proceedings WRS 2011, arXiv:1204.531

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

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

Industrial Experience Report on the Formal Specification of a Packet Filtering Language Using the K Framework

Many project-specific languages, including in particular filtering languages, are defined using nonformal specifications written in natural languages. This leads to ambiguities and errors in the specification of those languages. This paper reports on an industrial experiment on using a tool-supported language specification framework (K) for the formal specification of the syntax and semantics of a filtering language having a complexity similar to those of real-life projects. This experimentation aims at estimating, in a specific industrial setting, the difficulty and benefits of formally specifying a packet filtering language using a tool-supported formal approach

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