Reversible language extensions and their application in debugging

A range of methodologies and techniques are available to guide the design and implementation of language extensions and domainspecific languages. A simple yet powerful technique is based on source-tosource transformations interleaved across the compilation passes of a base language. Despite being a successful approach, it has the main drawback that the input source code is lost in the process. When considering the whole workflow of program development (warning and error reporting, debugging, or even program analysis), program translations are no more powerful than a glorified macro language. In this paper, we propose an augmented approach to language extensions for Prolog, where symbolic annotations are included in the target program. These annotations allow selectively reversing the translated code. We illustrate the approach by showing that coupling it with minimal extensions to a generic Prolog debugger allows us to provide users with a familiar, source-level view during the debugging of programs which use a variety of language extensions, such as functional notation, DCGs, or CLP{Q,R}

Unit testing for domain-specific languages, in

Abstract. Domain-specific languages (DSLs) offer several advantages by providing idioms that are similar to the abstractions found in a specific problem domain. However, a challenge is that tool support for DSLs is lacking when compared to the capabilities offered in general-purpose languages (GPLs), such as Java and C++. For example, support for unit testing a DSL program is absent and debuggers for DSLs are rare. This limits the ability of a developer to discover the existence of software errors and to locate them in a DSL program. Currently, software developers using a DSL are generally forced to test and debug their DSL programs using available GPL tools, rather than tools that are informed by the domain abstractions at the DSL level. This reduces the utility of DSL adoption and minimizes the benefits of working with higher abstractions, which can bring into question the suitability of using DSLs in the development process. This paper introduces our initial investigation into a unit testing framework that can be customized for specific DSLs through a reusable mapping of GPL testing tool functionality. We provide examples from two different DSL categories that serve as case studies demonstrating the possibilities of a unit testing engine for DSLs

Weaving a Debugging Aspect into Domain-Specific Language Grammars

A common trend in programming language specification is to generate various tools (e.g., compiler, editor, profiler, and debugger) from a grammar. In such a generative approach, it is desirable to have the definition of a programming language be modularized according to specific concerns specified in the grammar. However, it is often the case that the corresponding properties of the generated tools are scattered and tangled across the language specification. In this paper, separation of concerns within a programming language specification is demonstrated by considering debugging support within a domain-specific language (DSL). The paper first describes the use of AspectJ to weave the debugging semantics into the code created by a parser generator. The paper outlines several situations when the use of AspectJ is infeasible at separating language specification properties. To accommodate such situations, a second approach is presented that weaves the debugging support directly into a grammar specification using a program transformation engine. A case study for a simple DSL is presented to highlight the benefits of weaving across language specifications defined by grammars

Doctor of Philosophy

dissertationDomain-specific languages (DSLs) are increasingly popular, and there are a variety of ways to create a DSL. A DSL designer might write an interpreter from scratch, compile the DSL to another language, express DSL concepts using only the existing forms of an existing language, or implement DSL constructs using a language's extension capabilities, including macros. While extensible languages can offer the easiest opportunity for creating a DSL that takes advantage of the language's existing infrastructure, existing tools for debugging fail to adequately adapt the debugging experience to a given domain. This dissertation addresses the problem of debugging DSLs defined with macros and describes an event-oriented approach that works well with a macro-expansion view of language implementation. It pairs the mapping of DSL terms to host terms with an event mapping to convert primitive events back to domain-specific concepts. Domain-specific events can be further inspected or manipulated to construct domain-specific debuggers. This dissertation presents a core model of evaluation and events and also presents a language design-analogous to pattern-based notations for macros, but in the other direction-for describing how events in a DSL's expansion are mapped to events at the DSL's level. The domain-specific events can enable useful, domain-specific debuggers, and the dissertation introduces a design for a debugging framework to help with debugger construction. To validate the design of the debugging framework, a debugging framework, Ripple, is implemented, and this dissertation demonstrates that with a modest amount of work, Ripple can support building domain-specific debuggers

On Language Processors and Software Maintenance

This work investigates declarative transformation tools in the context of software maintenance. Besides maintenance of the language specification, evolution of a software language requires the adaptation of the software written in that language as well as the adaptation of the software that transforms software written in the evolving language. This co-evolution is studied to derive automatic adaptations of artefacts from adaptations of the language specification. Furthermore, AOP for Prolog is introduced to improve maintainability of language specifications and derived tools.Die Arbeit unterstützt deklarative Transformationswerkzeuge im Kontext der Softwarewartung. Neben der Wartung der Sprachbeschreibung erfordert die Evolution einer Sprache sowohl die Anpassung der Software, die in dieser Sprache geschrieben ist als auch die Anpassung der Software, die diese Software transformiert. Diese Koevolution wird untersucht, um automatische Anpassungen von Artefakten von Anpassungen der Sprachbeschreibungen abzuleiten. Weiterhin wird AOP für Prolog eingeführt, um die Wartbarkeit von Sprachbeschreibungen und den daraus abgeleiteten Werkzeugen zu erhöhen