A comprehensive operational semantics of the SCOOP programming model

TL;DR

This paper presents a detailed operational semantics for the SCOOP programming language, enabling implementation guidance and error detection, bridging the gap between formal models and real-world concurrent object-oriented programming.

Contribution

It provides a comprehensive, detailed semantics of SCOOP that supports implementation, error correction, and serves as a reference for operational semantics of object-oriented languages.

Findings

Guided implementation of SCOOP compiler and runtime

Detected and corrected errors in original specification

Established a manageable formal semantics framework

Abstract

Operational semantics has established itself as a flexible but rigorous means to describe the meaning of programming languages. Oftentimes, it is felt necessary to keep a semantics small, for example to facilitate its use for model checking by avoiding state space explosion. However, omitting many details in a semantics typically makes results valid for a limited core language only, leaving a wide gap towards any real implementation. In this paper we present a full-fledged semantics of the concurrent object-oriented programming language SCOOP (Simple Concurrent Object-Oriented Programming). The semantics has been found detailed enough to guide an implementation of the SCOOP compiler and runtime system, and to detect and correct a variety of errors and ambiguities in the original informal specification and prototype implementation. In our formal specification, we use abstract data types with preconditions and axioms to describe the state, and introduce a number of special run-time operations to model the runtime system with our inference rules. This approach allows us to make our large formal specification manageable, providing a first step towards reference documents for specifying object-oriented languages based on operational semantics.