• SCP 97 2015 [doi, bib, researchr, ]
    In this essay, I argue that linguistic abstraction should be used systematically as a tool to capture our emerging understanding of domains of computation. Moreover, to enable that systematic application, we need to capture our understanding of the domain of linguistic abstraction itself in higher-level meta languages. The argument is illustrated with examples from the SDF, Stratego, Spoofax, and WebDSL projects in which I explore these ideas.
  • Comp. Lang., Syst. \& Struct. 44 2015 [doi, bib, researchr, ]
    Language workbenches are environments for simplifying the creation and use of computer languages. The annual Language Workbench Challenge (LWC) was launched in 2011 to allow the many academic and industrial researchers in this area an opportunity to quantitatively and qualitatively compare their approaches. We first describe all four LWCs to date, before focussing on the approaches used, and results generated, during the third LWC. We give various empirical data for ten approaches from the third LWC. We present a generic feature model within which the approaches can be understood and contrasted. Finally, based on our experiences of the existing LWCs, we propose a number of benchmark problems for future LWCs.
  • OOPSLA 2015 [pdf, doi, bib, researchr, ]
    Federated conferences such as SPLASH are complex organizations composed of many parts (co-located conferences, symposia, and workshops), and are put together by many different people and committees. Developing the website for such a conference requires a considerable effort, and is often reinvented for each edition of a conference using software that provides little to no support for the domain. In this paper, we give a high-level overview of the design of Conf.Researchr.Org, a domain-specific content management system developed to support the production of large conference web sites, which is being used for the federated conferences of ACM SIGPLAN.
  • RTA 2015 [doi, bib, researchr, ]
    The formal semantics of a programming language and its implementation are typically separately defined, with the risk of divergence such that properties of the formal semantics are not properties of the implementation. In this paper, we present DynSem, a domain-specific language for the specification of the dynamic semantics of programming languages that aims at supporting both formal reasoning and efficient interpretation. DynSem supports the specification of the operational semantics of a language by means of statically typed conditional term reduction rules. DynSem supports concise specification of reduction rules by providing implicit build and match coercions based on reduction arrows and implicit term constructors. DynSem supports modular specification by adopting implicit propagation of semantic components from I-MSOS, which allows omitting propagation of components such as environments and stores from rules that do not affect those. DynSem supports the declaration of native operators for delegation of aspects of the semantics to an external definition or implementation. DynSem supports the definition of auxiliary meta-functions, which can be expressed using regular reduction rules and are subject to semantic component propagation. DynSem specifications are executable through automatic generation of a Java-based AST interpreter.
  • ESOP 2015 [doi, bib, researchr, ]
    We describe a language-independent theory for name binding and resolution, suitable for programming languages with complex scoping rules including both lexical scoping and modules. We formulate name resolution as a two-stage problem. First a language-independent scope graph is constructed using language-specific rules from an abstract syntax tree. Then references in the scope graph are resolved to corresponding declarations using a language-independent resolution process. We introduce a resolution calculus as a concise, declarative, and languageindependent specification of name resolution. We develop a resolution algorithm that is sound and complete with respect to the calculus. Based on the resolution calculus we develop language-independent definitions of α-equivalence and rename refactoring. We illustrate the approach using a small example language with modules. In addition, we show how our approach provides a model for a range of name binding patterns in existing languages.
  • Technical report TUD-SERG-2015-009, Software Engineering Research Group, Delft University of Technology, 2015 [pdf, bib, researchr, ]
    In previous work, we introduced scope graphs as a formalism for describing program binding structure and performing name resolution in an AST-independent way. In this paper, we show how to use scope graphs to build static semantic analyzers. We use constraints extracted from the AST to specify facts about binding, typing, and initialization. We treat name and type resolution as separate building blocks, but our approach can handle language constructs—such as record field access—for which binding and typing are mutually dependent. We also refine and extend our previous scope graph theory to address practical concerns including ambiguity checking and support for a wider range of scope relationships. We describe the details of constraint generation for a model language that illustrates many of the interesting static analysis issues associated with modules and records.
  • Technical report TUD-SERG-2015-006, Delft University of Technology, Software Engineering Research Group, 2015 [pdf, bib, researchr, ]
    We extend and combine two existing declarative formalisms, the scope graphs of Neron et al. and type constraint systems, to build a language-independent theory that can describe both name and type resolution for realistic languages with complex scope and typing rules. Unlike conventional static semantics presentations, our approach maintains a clear separation between scoping and typing concerns, while still be- ing able to handle language constructs, such as class field access, for which name and type resolution are necessarily intertwined. We define a constraint scheme that can express both typing and name binding constraints, and give a for- mal notion of constraint satisfiability together with a sound algorithm for finding solutions in important special cases. We describe the details of constraint generation for a model language that illustrates many of the interesting resolution issues associated with modules, classes, and records. Our constraint generator and solver have been implemented in the Spoofax Language Workbench.
  • IEEE Software 31(5) 2014 [doi, bib, researchr, ]
    IDEs are essential for programming language developers, and state-of-the-art IDE support is mandatory for programming languages to be successful. Although IDE features for mainstream programming languages are typically implemented manually, this often isn't feasible for programming languages that must be developed with significantly fewer resources. The Spoofax language workbench is a platform for developing textual programming languages with state-of-the-art IDE support. Spoofax is a comprehensive environment that integrates syntax definition, name binding, type analysis, program transformation, code generation, and declarative specification of IDE components. It also provides high-level languages for each of these aspects. These languages are highly declarative, abstracting over the implementation of IDE features and letting engineers focus on language design.
  • SLE 2014 [pdf, doi, bib, researchr, ]
    Object-oriented programming languages support concise navigation of relations represented by references. However, relations are not first-class citizens and bidirectional navigation is not supported. The relational paradigm provides first-class relations, but with bidirectional navigation through verbose queries. We present a systematic analysis of approaches to modeling and navigating relations. By unifying and generalizing the features of these approaches, we developed the design of a data modeling language that features first-class relations, n-ary relations, native multiplicities, bidirectional relations and concise navigation.
  • AOSD 2014 [doi, bib, researchr, ]
    A key problem in metaprogramming and specifically in generative programming is to guarantee that generated code is well-formed with respect to the context-free and context-sensitive constraints of the target language. We propose typesmart constructors as a dynamic approach to enforcing the well-formedness of generated code. A typesmart constructor is a function that is used in place of a regular constructor to create values, but it may reject the creation of values if the given data violates some language-specific constraint. While typesmart constructors can be implemented individually, we demonstrate how to derive them automatically from a grammar, so that the grammar remains the sole specification of a language's syntax and is not duplicated. We have integrated support for typesmart constructors into the run-time system of Stratego to enforce usage of typesmart constructors implicitly whenever a regular constructor is called. We evaluate the applicability, performance, and usefulness of typesmart constructors for syntactic constraints in a compiler for MiniJava developed with Spoofax and in various language extensions of Java and Haskell implemented with SugarJ and SugarHaskell.
  • AOSD 2014 [doi, bib, researchr, ]
    Program generators and transformations are hard to implement correctly, because the implementation needs to generically describe how to construct programs, for example, using templates or rewrite rules. We apply dynamic analysis to program generators in order to support developers in finding bugs and identifying the source of the bug. Our analysis focuses on syntactic language constraints and checks that generated programs are syntactically well-formed. To retain a language's grammar as the unique specification of the language's syntax, we devised mechanisms to derive the analysis from the grammar. Moreover, we designed a run-time system to support the modular activation/deactivation of the analysis, so that generators do not require adaption. We have implemented the analysis for the Stratego term-rewriting language and applied it in case studies based on Spoofax and SugarJ.
  • AOSD 2014 [doi, bib, researchr, ]
    Effectively applying linguistic abstraction to emerging domains of computation requires the ability to rapidly develop software languages. However, a software language is a complex software system in its own right and can take significant effort to design and implement. We are currently investigating a radical separation of concerns in language definition by designing high-level declarative meta-languages specialized to the various concerns of language definition that can be used as the single source of production quality (incremental) semantic operations and as a model for reasoning about language properties.
  • OOPSLA 2014 [pdf, doi, bib, researchr, ]
    The realization of a language design requires multiple artifacts that redundantly encode the same information. This entails significant effort for language implementors, and often results in late detection of errors in language definitions. In this paper we present a proof-of-concept language designer's workbench that supports generation of IDEs, interpreters, and verification infrastructure from a single source. This constitutes a first milestone on the way to a system that fully automates language implementation and verification.
  • SoSyM 12(1) 2013 [doi, bib, researchr, ]
    Data validation rules constitute the constraints that data input and processing must adhere to in addition to the structural constraints imposed by a data model. Web modeling tools do not make all types of data validation explicit in their models, hampering full code generation and model expressivity. Web application frameworks do not offer a consistent interface for data validation. In this paper, we present a solution for the integration of declarative data validation rules with user interface models in the domain of web applications, unifying syntax, mechanisms for error handling, and semantics of validation checks, and covering value well-formedness, data invariants, input assertions, and action assertions. We have implemented the approach in WebDSL, a domain-specific language for the definition of web applications.
  • SCP 78(10) 2013 [doi, bib, researchr, ]
    Attribute grammars are a powerful specification paradigm for many language processing tasks, particularly semantic analysis of programming languages. Recent attribute grammar systems use dynamic scheduling algorithms to evaluate attributes on demand. In this paper, we show how to remove the need for a generator, by embedding a dynamic approach in a modern, object-oriented and functional programming language. The result is a small, lightweight attribute grammar library that is part of our larger Kiama language processing library. Kiama’s attribute grammar library supports a range of advanced features including cached, uncached, higher order, parameterised and circular attributes. Forwarding is available to modularise higher order attributes and decorators abstract away from the details of attribute value propagation. Kiama also implements new techniques for dynamic extension and variation of attribute equations. We use the Scala programming language because of its support for domain-specific notations and emphasis on scalability. Unlike generators with specialised notation, Kiama attribute grammars use standard Scala notations such as pattern-matching functions for equations, traits and mixins for composition and implicit parameters for forwarding. A benchmarking exercise shows that our approach is practical for realistic language processing.
  • This book covers DSL Design, Implementation and Use of DSL in detail. It consists of four parts. Part 1 introduces DSLs in general and discusses their advantages and drawbacks. It also defines important terms and concepts and introduces the case studies used in the most of the re-mainder of the book. Part 2 discusses the design of DSLs – independent of implementation techniques. It discusses seven design dimensions, explains a number of reusable language paradigms and points out a number of process-related issues. Part 3 provides details about the implementation of DSLs with lots of code. It uses three state-of-the-art but quite different language workbenches: Jet-Brains MPS, Eclipse Xtext and TU Delft’s Spoofax. Part 4 discusses the use of DSLs for requirements, architecture, implementation and product line engineering, as well as their roles as a developer utility and for implementing business logic.
  • ICMT 2013 [doi, bib, researchr, ]
    In modern Integrated Development Environments (IDEs), textual editors are interactive and can handle intermediate, incomplete, or otherwise erroneous texts while still providing editor services such as syntax highlighting, error marking, outline views, and hover help. In this paper, we present an approach for the robust synchronization of interactive textual and graphical editors. The approach recovers from errors during parsing and text-to-model synchronization, preserves textual and graphical layout in the presence of erroneous texts and models, and provides synchronized editor services such as selection sharing and navigation between editors. It was implemented for synchronizing textual editors generated by the Spoofax language workbench and graphical editors generated by the Graphical Modeling Framework.
  • SLE 2013 [doi, bib, researchr, ]
    IDEs depend on incremental name and type analysis for responsive feedback for large projects. In this paper, we present a language-independent approach for incremental name and type analysis. Analysis consists of two phases. The first phase analyzes lexical scopes and binding instances and creates deferred analysis tasks. A task captures a single name resolution or type analysis step. Tasks might depend on other tasks and are evaluated in the second phase. Incrementality is supported on file and task level. When a file changes, only this file is recollected and only those tasks are reevaluated, which are affected by the changes in the collected data. The analysis does neither re-parse nor re-traverse unchanged files, even if they are affected by changes in other files. We implemented the approach as part of the Spoofax Language Workbench and evaluated it for the WebDSL web programming language.
  • SLE 2013 [doi, bib, researchr, ]
    Language workbenches are tools that provide high-level mechanisms for the implementation of (domain-specific) languages. Language workbenches are an active area of research that also receives many contributions from industry. To compare and discuss existing language workbenches, the annual Language Workbench Challenge was launched in 2011. Each year, participants are challenged to realize a given domain-specific language with their workbenches as a basis for discussion and comparison. In this paper, we describe the state of the art of language workbenches as observed in the previous editions of the Language Workbench Challenge. In particular, we capture the design space of language workbenches in a feature model and show where in this design space the participants of the 2013 Language Workbench Challenge reside. We compare these workbenches based on a DSL for questionnaires that was realized in all workbenches.
  • TOPLAS 34(4) 2012 [doi, bib, researchr, ]
    Integrated development environments (IDEs) increase programmer productivity, providing rapid, interactive feedback based on the syntax and semantics of a language. Unlike conventional parsing algorithms, scannerless generalized-LR parsing supports the full set of context-free grammars, which is closed under composition, and hence can parse languages composed from separate grammar modules. To apply this algorithm in an interactive environment, this paper introduces a novel error recovery mechanism. Our approach is language-independent, and relies on automatic derivation of recovery rules from grammars. By taking layout information into consideration it can efficiently suggest natural recovery suggestions.
  • ASE 2012 [doi, bib, researchr, ]
    Evaluation of parse error recovery techniques is an open problem. The community lacks objective standards and methods to measure the quality of recovery results. This paper proposes an automated technique for recovery evaluation that offers a solution for two main problems in this area. First, a representative testset is generated by a mutation based fuzzing technique that applies knowledge about common syntax errors. Secondly, the quality of the recovery results is automatically measured using an oracle-based evaluation technique. We evaluate the validity of our approach by comparing results obtained by automated evaluation with results obtained by manual inspection. The evaluation shows a clear correspondence between our quality metric and human judgement.
  • Companion to the 27th Annual ACM SIGPLAN Conference on Object-Oriented Programming, Systems, Languages, and Applications, OOPSLA 2011, part of SPLASH 2012, Tucson, AR, USA, October 19 - 26, 2012 2012 [doi, bib, researchr]
  • LDTA 2012 [doi, bib, researchr, ]
    Syntax discoverability has been a crucial advantage of structure editors for new users of a language. Despite this advantage, structure editors have not been widely adopted. Based on immediate parsing and analyses, modern textual code editors are also increasingly syntax-aware: structure and textual editors are converging into a new editing paradigm that combines text and templates. Current text-based language workbenches require redundant specification of the ingredients for a template-based editor, which is detrimental to the quality of syntactic completion, as consistency and completeness of the definition cannot be guaranteed. In this paper we describe the design and implementation of a specification language for syntax definition based on templates. It unifies the specification of parsers, unparsers and template-based editors. We evaluate the template language by application to two domain-specific languages used for tax benefits and mobile applications.
  • SLE 2012 [doi, bib, researchr, ]
    In textual software languages, names are used to reference elements like variables, methods, classes, etc. Name resolution analyses these names in order to establish references between definition and use sites of elements. In this paper, we identify recurring patterns for name bindings in programming languages and introduce a declarative metalanguage for the specification of name bindings in terms of namespaces, definition sites, use sites, and scopes. Based on such declarative name binding specifications, we provide a language-parametric algorithm for static name resolution during compile-time. We discuss the integration of the algorithm into the Spoofax Language Workbench and show how its results can be employed in semantic editor services like reference resolution, constraint checking, and content completion.
  • OOPSLA 2012 [doi, bib, researchr, ]
    Software is rapidly moving from the desktop to the Web. The Web provides a generic user interface that allows ubiquitous access, instant collaboration, integration with other online services, and avoids installation and configuration on desktop computers. For software development, the Web presents a shift away from developer workstations as a silo, and has the promise of closer collaboration and improved feedback through innovations in Web-based interactive development environments (IDEs). Moving IDEs to the Web is not just a matter of porting desktop IDEs; a fundamental reconsideration of the IDE architecture is necessary in order to realize the full potential that the combination of modern IDEs and the Web can offer. This paper discusses research challenges and opportunities in this area, guided by a pilot study of a web IDE implementation.
  • LDTA 2012 [doi, bib, researchr, ]
    The implementation of refactorings for new languages requires considerable effort from the language developer. We aim at reducing that effort by using language generic techniques. This paper focuses on behavior preservation, in particular the preservation of static name bindings. To detect name binding violations, we implement a technique that reuses the name analysis defined in the compiler front end. Some languages offer the possibility to access variables using qualified names. As a refinement to violation detection, we show that name analysis can be defined as a reusable traversal strategy that can be applied to restore name bindings by creating qualified names. These techniques offer an efficient and reliable solution; the semantics of the language is implemented only once, with the compiler being the single source of truth. We evaluate our approach by implementing a language generic rename refactoring, which we apply to two domain specific languages and a subset of the Java language.
  • JSC 46(2) 2011 [doi, bib, researchr, ]
    Modern web application development frameworks provide web application developers with high-level abstractions to improve their productivity. However, their support for static verification of applications is limited. Inconsistencies in an application are often not detected statically, but appear as errors at run-time. The reports about these errors are often obscure and hard to trace back to the source of the inconsistency. A major part of this inadequate consistency checking can be traced back to the lack of linguistic integration of these frameworks. Parts of an application are defined with separate domain-specific languages, which are not checked for consistency with the rest of the application. Examples include regular expressions, query languages and XML-based languages for definition of user interfaces. We give an overview and analysis of typical problems arising in development with frameworks for web application development, with Ruby on Rails, Lift and Seam as representatives. To remedy these problems, in this paper, we argue that domain-specific languages should be designed from the ground up with static verification and cross-aspect consistency checking in mind, providing linguistic integration of domain-specific sub-languages. We show how this approach is applied in the design of WebDSL, a domain-specific language for web applications, by examining how its compiler detects inconsistencies not caught by web frameworks, providing accurate and clear error messages. Furthermore, we show how this consistency analysis can be expressed with a declarative rule-based approach using the Stratego transformation language.
  • GPCE 2011 [doi, bib, researchr, ]
    WebDSL is a domain-specific language for the implementation of dynamic web applications with a rich data model. It provides developers with object-oriented data modeling concepts but abstracts over implementation details for persisting application data in relational databases. When the underlying data model of an application evolves, persisted application data has to be migrated. While implementing migration at the database level breaks the abstractions provided by WebDSL, an implementation at the data model level requires to intermingle migration with application code. In this paper, we present a domain-specific language for the coupled evolution of data models and application data. It allows to specify data model evolution as a separate concern at the data model level and can be compiled to migration code at the database level. Its linguistic integration with WebDSL enables static checks for evolution validity and correctness.
  • SLE 2011 [doi, bib, researchr, ]
    Metamodel evolution requires model migration. To correctly migrate models, evolution needs to be made explicit. Manually describing evolution is error-prone and redundant. Metamodel matching offers a solution by automatically detecting evolution, but is only capable of detecting primitive evolution steps. In practice, primitive evolution steps are jointly applied to form a complex evolution step, which has the same effect on a metamodel as the sum of its parts, yet generally has a different effect in migration. Detection of complex evolution is therefore needed. In this paper, we present an approach to reconstruct complex evolution between two metamodel versions, using a matching result as input. It supports operator dependencies and mixed, overlapping, and incorrectly ordered complex operator components. It also supports interference between operators, where the effect of one operator is partially or completely hidden from the target metamodel by other operators.
  • GPCE 2011 [doi, bib, researchr, ]
    Large software projects consist of code written in a multitude of different (possibly domain-specific) languages, which are often deeply interspersed even in single files. While many proposals exist on how to integrate languages semantically and syntactically, the question of how to support this scenario in integrated development environments (IDEs) remains open: How can standard IDE services, such as syntax highlighting, outlining, or reference resolving, be provided in an extensible and compositional way, such that an open mix of languages is supported in a single file? Based on our library-based syntactic extension language for Java, SugarJ, we propose to make IDEs extensible by organizing editor services in editor libraries. Editor libraries are libraries written in the object language, SugarJ, and hence activated and composed through regular import statements on a file-by-file basis. We have implemented an IDE for editor libraries on top of SugarJ and the Eclipse-based Spoofax language workbench. We have validated editor libraries by evolving this IDE into a fully-fledged and schema-aware XML editor as well as an extensible Latex editor, which we used for writing this paper.
  • Companion to the 26th Annual ACM SIGPLAN Conference on Object-Oriented Programming, Systems, Languages, and Applications, OOPSLA 2011, part of SPLASH 2011, Portland, OR, USA, October 22 - 27, 2011 2011 [doi, bib, researchr]
  • OOPSLA 2011 [doi, bib, researchr, ]
    SugarJ is a Java-based programming language that provides extensible surface syntax, static analyses, and IDE support. SugarJ extensions are organized as libraries; conventional import statements suffice to activate and compose language extensions. We demonstrate how programmers can use SugarJ to modularly extend Java's syntax, semantic analyses and IDE support.
  • OOPSLA 2011 [doi, bib, researchr, ]
    The reliability of compilers, interpreters, and development environments for programming languages is essential for effective software development and maintenance. They are often tested only as an afterthought. Languages with a smaller scope, such as domain-specific languages, often remain untested. General-purpose testing techniques and test case generation methods fall short in providing a low-threshold solution for test-driven language development. In this paper we introduce the notion of a language-parametric testing language (LPTL) that provides a reusable, generic basis for declaratively specifying language definition tests. We integrate the syntax, semantics, and editor services of a language under test into the LPTL for writing test inputs. This paper describes the design of an LPTL and the tool support provided for it, shows use cases using examples, and describes our implementation in the form of the Spoofax testing language.
  • GPCE 2011 [doi, bib, researchr, ]
    Tool support is vital to the effectiveness of domain-specific languages. With language workbenches, domain-specific languages and their tool support can be generated from a combined, high-level specification. This paper shows how such a specification can be extended to describe a debugger for a language. To realize this, we introduce a meta-language for coordinating the debugger that abstracts over the complexity of writing a debugger by hand. We describe the implementation of a language-parametric infrastructure for debuggers that can be instantiated based on this specification. The approach is implemented in the Spoofax language workbench and validated through realistic case studies with the Stratego transformation language and the WebDSL web programming language.
  • OOPSLA 2011 [doi, bib, researchr, ]
    Mobl is a new language designed to declaratively construct mobile web applications. Mobl integrates languages for user interface design, styling, data modeling, querying and application logic into a single, unified language that is flexible, expressive, enables early detection of errors, and has good IDE support.
  • SLE 2011 [doi, bib, researchr, ]
    Transformations and semantic analysis for source-to-source transformations such as refactorings are most effectively implemented using an abstract representation of the source code. An intrinsic limitation of transformation techniques based on abstract syntax trees is the loss of layout, i.e. comments and whitespace. This is especially relevant in the context of refactorings, which produce source code for human consumption. In this paper, we present an algorithm for fully automatic source code reconstruction for source-to-source transformations. The algorithm preserves the layout and comments of the unaffected parts and reconstructs the indentation of the affected parts, using a set of clearly defined heuristic rules to handle comments.
  • OOPSLA 2011 [doi, bib, researchr, ]
    The Spoofax testing language provides a new approach to testing domain-specific languages as they are developed. It allows test cases to be written using fragments of the language under test, providing full IDE support for writing test cases and supporting tests for language syntax, semantics, and editor services.
  • SPLC 2011 [doi, bib, researchr, ]
    This paper investigates the application of domain-specific languages in product line engineering (PLE). We start by analyzing the limits of expressivity of feature models. Feature models correspond to context-free grammars without recursion, which prevents the expression of multiple instances and references. We then show how domain-specific languages (DSLs) can serve as a middle ground between feature modeling and programming. They can be used in cases where feature models are too limited, while keeping the separation between problem space and solution space provided by feature models. We then categorize useful combinations between configuration with feature model and construction with DSLs and provide an integration of DSLs into the conceptual framework of PLE. Finally we show how use of a consistent, unified formalism for models, code, and configuration can yield important benefits for managing variability and trace ability. We illustrate the concepts with several examples from industrial case studies.
  • Programming the Mobile Web with Mobl
    Technical report TUD-SERG-2011-01, Delft University of Technology, 2011 [bib, researchr, ]
    A new generation of mobile touch devices, such as the iPhone, Android and iPad, are equipped with powerful, modern browsers. However, regular websites are not optimized for the specific features and constraints of these devices, such as limited screen estate, unreliable Internet access, touch-based interaction patterns, and features such as GPS. While recent advances in web technology enable web developers to build web applications that take advantage of the unique properties of mobile devices, developing such applications is not a clean, well-integrated experience. Developers are required to use many loosely coupled languages with limited tool support and application code is often verbose and imperative. We introduce mobl, a new language designed to declaratively construct mobile web applications. Mobl integrates languages for user interface design, data modeling and querying, scripting and web services into a single, unified language that is flexible, expressive, enables early detection of errors, and has good IDE support. We illustrate the design of the language with the implementation of ConfPlan, an application for keeping track of the schedule of conference events.
  • SCP 75(7) 2010 [doi, bib, researchr, ]
    Software written in one language often needs to construct sentences in another language, such as SQL queries, XML output, or shell command invocations. This is almost always done using unhygienic string manipulation, the concatenation of constants and client-supplied strings. A client can then supply specially crafted input that causes the constructed sentence to be interpreted in an unintended way, leading to an injection attack. We describe a more natural style of programming that yields code that is impervious to injections by construction. Our approach embeds the grammars of the guest languages (e.g. SQL) into that of the host language (e.g. Java) and automatically generates code that maps the embedded language to constructs in the host language that reconstruct the embedded sentences, adding escaping functions where appropriate. This approach is generic, meaning that it can be applied with relative ease to any combination of context-free host and guest languages.
  • ENTCS 253(7) 2010 [doi, bib, researchr, ]
    Modern IDEs increase developer productivity by incorporating many different kinds of editor services. These can be purely syntactic, such as syntax highlighting, code folding, and an outline for navigation; or they can be based on the language semantics, such as in-line type error reporting and resolving identifier declarations. Building all these services from scratch requires both the extensive knowledge of the sometimes complicated and highly interdependent APIs and extension mechanisms of an IDE framework, and an in-depth understanding of the structure and semantics of the targeted language. This paper describes Spoofax/IMP, a meta-tooling suite that provides high-level domain-specific languages for describing editor services, relieving editor developers from much of the framework-specific programming. Editor services are defined as composable modules of rules coupled to a modular SDF grammar. The composability provided by the SGLR parser and the declaratively defined services allows embedded languages and language extensions to be easily formulated as additional rules extending an existing language definition. The service definitions are used to generate Eclipse editor plugins. We discuss two examples: an editor plugin for WebDSL, a domain-specific language for web applications, and the embedding of WebDSL in Stratego, used for expressing the (static) semantic rules of WebDSL.
  • IEEE Software 27(5) 2010 [doi, bib, researchr, ]
    WebDSL is a domain-specific language for Web information systems that maintains separation of concerns while integrating its sublanguages, enabling consistency checking and reusing common language concepts.
  • SoSyM 9(3) 2010 [doi, bib, researchr, ]
    The realization of model-driven software development requires effective techniques for implementing code generators for domain-specific languages. This paper identifies techniques for improving separation of concerns in the implementation of generators. The core technique is code generation by model transformation, that is, the generation of a structured representation (model) of the target program instead of plain text. This approach enables the transformation of code after generation, which in turn enables the extension of the target language with features that allow better modularity in code generation rules. The technique can also be applied to ‘internal code generation’ for the translation of high-level extensions of a DSL to lower-level constructs within the same DSL using model-to-model transformations. This paper refines our earlier description of code generation by model transformation with an improved architecture for the composition of model-to-model normalization rules, solving the problem of combining type analysis and transformation. Instead of coarse-grained stages that alternate between normalization and type analysis, we have developed a new style of type analysis that can be integrated with normalizing transformations in a fine-grained manner. The normalization strategy has a simple extension interface and integrates non-local, context-sensitive transformation rules. We have applied the techniques in a realistic case study of domain-specific language engineering, i.e. the code generator for WebDSL, using Stratego, a high-level transformation language that integrates model-to-model, model-to-code, and code-to-code transformations.
  • OOPSLA 2010 [pdf, doi, bib, researchr, ]
    Spoofax is a language workbench for efficient, agile development of textual domain-specific languages with state-of-the-art IDE support. Spoofax integrates language processing techniques for parser generation, meta-programming, and IDE development into a single environment. It uses concise, declarative specifications for languages and IDE services. In this paper we describe the architecture of Spoofax and introduce idioms for high-level specifications of language semantics using rewrite rules, showing how analyses can be reused for transformations, code generation, and editor services such as error marking, reference resolving, and content completion. The implementation of these services is supported by language-parametric editor service classes that can be dynamically loaded by the Eclipse IDE, allowing new languages to be developed and used side-by-side in the same Eclipse environment.
  • SLE 2010 [doi, bib, researchr, ]
    In meta-programming with concrete object syntax, meta programs can be written using the concrete syntax of manipulated programs. Quotations of concrete syntax fragments and anti-quotations for meta-level expressions and variables are used to manipulate the abstract representation of programs. These small, isolated fragments are often ambiguous and must be explicitly disambiguated with quotation tags or types, using names from the non-terminals of the object language syntax. Discoverability of these names has been an open issue, as they depend on the (grammar) implementation and are not part of the concrete syntax of a language. Based on advances in interactive development environments, we introduce interactive disambiguation to address this issue, providing real-time feedback and proposing quick fixes in case of ambiguities.
  • OOPSLA 2010 [doi, bib, researchr, ]
    Syntax definitions are pervasive in modern software systems, and serve as the basis for language processing tools like parsers and compilers. Mainstream parser generators pose restrictions on syntax definitions that follow from their implementation algorithm. They hamper evolution, maintainability, and compositionality of syntax definitions. The pureness and declarativity of syntax definitions is lost. We analyze how these problems arise for different aspects of syntax definitions, discuss their consequences for language engineers, and show how the pure and declarative nature of syntax definitions can be regained.
  • OOPSLA 2010 [doi, bib, researchr, ]
    Spoofax is a language workbench for efficient, agile development of textual domain-specific languages with state-of-the-art IDE support. It provides a comprehensive environment that integrates syntax definition, program transformation, code generation, and declarative specification of IDE components.
  • OOPSLA 2010 [doi, bib, researchr, ]
    Domain-specific languages (DSLs) provide high expressive power focused on a particular problem domain. They provide linguistic abstractions and specialized syntax specifically designed for a domain, allowing developers to avoid boilerplate code and low-level implementation details. Language workbenches are tools that integrate all aspects of the definition of domain-specific or general-purpose software languages and the creation of a programming environment from such a definition. To count as a language workbench, a tool needs to satisfy basic requirements for the integrated definition of syntax, semantics, and editor services, and preferably also support language extension and composition. Within these requirements there is ample room for variation in the design of a language workbench. In this tutorial, we give an introduction to the state of the art in textual DSLs and language workbenches. We discuss the main requirements and variation points in the design of language workbenches, and describe two points in the design space using two state-of-the-art language workbenches. Spoofax is an example of a parser-based language workbench, while MPS represents language workbenches based on projectional editors.
  • SCAM 2010 [doi, bib, researchr, ]
    Software platforms such as the Java Virtual Machine or the CLR. NET virtual machine have their own ecosystem of a core programming language or instruction set, libraries, and developer community. Programming languages can target multiple software platforms to increase interoperability or to boost performance. Introducing a new compiler backend for a language is the first step towards targeting a new platform, translating the language to the platform's language or instruction set. Programs written in modern languages generally make extensive use of APIs, based on the runtime system of the software platform, introducing additional portability concerns. They may use APIs that are implemented by platform-specific libraries. Libraries may perform platform-specific operations, make direct native calls, or make assumptions about performance characteristics of operations or about the file system. This paper proposes to use aspect weaving to invasively adapt programs and libraries to address such portability concerns, and identifies four classes of aspects for this purpose. We evaluate this approach through a case study where we retarget the Stratego program transformation language towards the Java Virtual Machine.
  • Technical report TUD-SERG-2010-010, Software Engineering Research Group, Delft University of Technology, 2010 [doi, bib, researchr, ]
    This paper describes the workflow for performing systematic literature reviews with the researchr digital library environment.
  • ENTCS 238(3) 2009 [doi, bib, researchr, ]
    The 2nd Rewrite Engines Competition (REC) was celebrated as part of the 7th Workshop on Rewriting Logic and its Applications (WRLA 2008). In this edition of the competition participated ve systems, namely ASF+SDF, Maude, Stratego/XT, Termware, and Tom. We explain here how the competition was organized and conducted, and present its main results and conclusions.
  • CC 2009 [doi, bib, researchr, ]
    Attribute grammars are a powerful specification formalism for tree-based computation, particularly for software language processing. Various extensions have been proposed to abstract over common patterns in attribute grammar specifications. These include various forms of copy rules to support non-local dependencies, collection attributes, and expressing dependencies that are evaluated to a fixed point. Rather than implementing extensions natively in an attribute evaluator, we propose attribute decorators that describe an abstract evaluation mechanism for attributes, making it possible to provide such extensions as part of a library of decorators. Inspired by strategic programming, decorators are specified using generic traversal operators. To demonstrate their effectiveness, we describe how to employ decorators in name, type, and flow analysis.
  • SLE 2009 [doi, bib, researchr, ]
    Module systems, separate compilation, deployment of binary components, and dynamic linking have enjoyed wide acceptance in programming languages and systems. In contrast, the syntax of languages is usually defined in a non-modular way, cannot be compiled separately, cannot easily be combined with the syntax of other languages, and cannot be deployed as a component for later composition. Grammar formalisms that do support modules use whole program compilation. Current extensible compilers focus on source-level extensibility, which requires users to compile the compiler with a specific configuration of extensions. A compound parser needs to be generated for every combination of extensions. The generation of parse tables is expensive, which is a particular problem when the composition configuration is not fixed to enable users to choose language extensions. In this paper we introduce an algorithm for parse table composition to support separate compilation of grammars to parse table components. Parse table components can be composed (linked) efficiently at runtime, i.e. just before parsing. While the worst-case time complexity of parse table composition is exponential (like the complexity of parse table generation itself), for realistic language combination scenarios involving grammars for real languages, our parse table composition algorithm is an order of magnitude faster than computation of the parse table for the combined grammars.
  • OOPSLA 2009 [doi, bib, researchr, ]
    WebDSL is a domain-specific language for the development of web applications that integrates data-models, user-interface models, actions, validation, access control, and workflow. The compiler verifies the consistency of applications and generates complete implementations in Java or Python. We illustrate the key concepts of the language with a small web application.
  • CLOUD 2009 [doi, bib, researchr, ]
    Hospital environments are currently primarily device-oriented: software services are installed, often manually, on specific devices. For instance, an application to view MRI scans may only be available on a limited number of workstations. The medical world is changing to a service-oriented environment, which means that every software service should be available on every device. However, these devices have widely varying capabilities, ranging from powerful workstations to PDAs, and high-bandwidth local machines to low-bandwidth remote machines. To support running applications in such an environment, we need to treat the hospital machines as a cloud, where components of the application are automatically deployed to machines in the cloud with the required capabilities and connectivity. In this paper, we suggest an architecture for applications in such a cloud, in which components are reliably and automatically deployed on the basis of a declarative model of the application using the Nix package manager.
  • SLE 2009 [doi, bib, researchr, ]
    Parser generators are an indispensable tool for rapid language development. However, they often fall short of the finesse of a hand-crafted parser, built with the language semantics in mind. One area where generated parsers have provided unsatisfactory results is that of error recovery. Good error recovery is both natural, giving recovery suggestions in line with the intention of the programmer; and flexible, allowing it to be adapted according to language insights and language changes. This paper describes a novel approach to error recovery, taking into account not only the context-free grammar, but also indentation usage. We base our approach on an extension of the SGLR parser that supports fine-grained error recovery rules and can be used to parse complex, composed languages. We take a divide-and-conquer approach to error recovery: using indentation, erroneous regions of code are identified. These regions constrain the search space for applying recovery rules, improving performance and ensuring recovery suggestions local to the error. As a last resort, erroneous regions can be discarded. Our approach also integrates bridge parsing to provide more accurate suggestions for indentation-sensitive language constructs such as scopes. We evaluate our approach by comparison with the JDT Java parser used in Eclipse.
  • OOPSLA 2009 [doi, bib, researchr, ]
    Integrated development environments (IDEs) increase programmer productivity, providing rapid, interactive feedback based on the syntax and semantics of a language. A heavy burden lies on developers of new languages to provide adequate IDE support. Code generation techniques provide a viable, efficient approach to semi-automatically produce IDE plugins. Key components for the realization of plugins are the language's grammar and parser. For embedded languages and language extensions, constituent IDE plugin modules and their grammars can be combined. Unlike conventional parsing algorithms, scannerless generalized-LR parsing supports the full set of context-free grammars, which is closed under composition, and hence can parse language embeddings and extensions composed from separate grammar modules. To apply this algorithm in an interactive environment, this paper introduces a novel error recovery mechanism, which allows it to be used with files with syntax errors -- common in interactive editing. Error recovery is vital for providing rapid feedback in case of syntax errors, as most IDE services depend on the parser -- from syntax highlighting to semantic analysis and cross-referencing. We base our approach on the principles of island grammars, and derive permissive grammars with error recovery productions from normal SDF grammars. To cope with the added complexity of these grammars, we adapt the parser to support backtracking. We evaluate the recovery quality and performance of our approach using a set of composed languages, based on Java and Stratego.
  • SLE 2009 [doi, bib, researchr, ]
    Intermediate languages are used in compiler construction to simplify retargeting compilers to multiple machine architectures. In the implementation of domain-specific languages (DSLs), compilers typically generate high-level source code, rather than low-level machine instructions. DSL compilers target a software platform, i.e. a programming language with a set of libraries, deployable on one or more operating systems. DSLs enable targeting multiple software platforms if its abstractions are platform independent. While transformations from DSL to each targeted platform are often conceptually very similar, there is little reuse between transformations due to syntactic and API differences of the target platforms, making supporting multiple platforms expensive. In this paper, we discuss the design and implementation of PIL, a Platform Independent Language, an intermediate language providing a layer of abstraction between DSL and target platform code, abstracting from syntactic and API differences between platforms, thereby removing the need for platform-specific transformations. We discuss the use of PIL in an implemementation of WebDSL, a DSL for building web applications.
  • SCP 72(1-2) 2008 [doi, bib, researchr, ]
    Stratego/XT is a language and toolset for program transformation. The Stratego language provides rewrite rules for expressing basic transformations, programmable rewriting strategies for controlling the application of rules, concrete syntax for expressing the patterns of rules in the syntax of the object language, and dynamic rewrite rules for expressing context-sensitive transformations, thus supporting the development of transformation components at a high level of abstraction. The XT toolset offers a collection of flexible, reusable transformation components, and tools for generating such components from declarative specifications. Complete program transformation systems are composed from these components.
  • ENTCS 203(2) 2008 [doi, bib, researchr, ]
    Program transformation systems provide powerful analysis and transformation frameworks as well as concise languages for language processing, but instantiating them for every subject language is an arduous task, most often resulting in half-completed frontends. Compilers provide mature frontends with robust parsers and type checkers, but solving language processing problems in general-purpose languages without transformation libraries is tedious. Reusing these frontends with existing transformation systems is therefore attractive. However, for this reuse to be optimal, the functional logic found in the frontend should be exposed to the transformation system – simple data serialization of the abstract syntax tree is not enough, since this fails to expose important compiler functionality, such as import graphs, symbol tables and the type checker. In this paper, we introduce a novel and general technique for combining term-based transformation systems with existing language frontends. The technique is presented in the context of a scriptable analysis and transformation framework for Java built on top of the Eclipse Java compiler. The framework consists of an adapter automatically extracted from the abstract syntax tree of the compiler and an interpreter for the Stratego program transformation language. The adapter allows the Stratego interpreter to rewrite directly on the compiler AST. We illustrate the applicability of our system with scripts written in Stratego that perform framework and library-specific analyses and transformations.
  • ENTCS 203(2) 2008 [doi, bib, researchr, ]
    A wide range of parser generators are used to generate parsers for programming languages. The grammar formalisms that come with parser generators provide different approaches for defining operator precedence. Some generators (e.g. YACC) support precedence declarations, others require the grammar to be unambiguous, thus encoding the precedence rules. Even if the grammar formalism provides precedence rules, a particular grammar might not use it. The result is grammar variants implementing the same language. For the C language, the GNU Compiler uses YACC with precedence rules, the C-Transformers uses SDF without priorities, while the SDF library does use priorities. For PHP, Zend uses YACC with precedence rules, whereas PHP-front uses SDF with priority and associativity declarations. The variance between grammars raises the question if the precedence rules of one grammar are compatible with those of another. This is usually not obvious, since some languages have complex precedence rules. Also, for some parser generators the semantics of precedence rules is defined operationally, which makes it hard to reason about their effect on the defined language. We present a method and tool for comparing the precedence rules of different grammars and parser generators. Although it is undecidable whether two grammars define the same language, this tool provides support for comparing and recovering precedence rules, which is especially useful for reliable migration of a grammar from one grammar formalism to another. We evaluate our method by the application to non-trivial mainstream programming languages, such as PHP and C.
  • ICMT 2008 [doi, bib, researchr, ]
    The realization of model-driven software development requires effective techniques for implementing code generators. In this paper, we present a case study of code generation by model transformation with Stratego, a high-level transformation language based on the paradigm of rewrite rules with programmable strategies that integrates model-to-model, model-to-code, and code-to-code transformations. The use of concrete object syntax guarantees syntactic correctness of code patterns, and enables the subsequent transformation of generated code. The composability of strategies supports two dimensions of transformation modularity. Vertical modularity is achieved by designing a generator as a pipeline of model-to-model transformations that gradually transforms a high-level input model to an implementation. Horizontal modularity is achieved by supporting the definition of plugins which implement all aspects of a language feature. We discuss the application of these techniques in the implementation of WebDSL, a domain-specific language for dynamic web applications with a rich data model.
  • OOPSLA 2008 [doi, bib, researchr, ]
    Language extensions increase programmer productivity by providing concise, often domain-specific syntax, and support for static verification of correctness, security, and style constraints. Language extensions can often be realized through translation to the base language, supported by preprocessors and extensible compilers. However, various kinds of extensions require further adaptation of a base compiler's internal stages and components, for example to support separate compilation or to make use of low-level primitives of the platform (e.g., jump instructions or unbalanced synchronization). To allow for a more loosely coupled approach, we propose an open compiler model based on normalization steps from a high-level language to a subset of it, the core language. We developed such a compiler for a mixed Java and (core) bytecode language, and evaluate its effectiveness for composition mechanisms such as traits, as well as statement-level and expression-level language extensions.
  • When Frameworks Let You Down. Platform-Imposed Constraints on the Design and Evolution of Domain-Specific Languages
    DSM 2008 [bib, researchr, ]
    Application frameworks encapsulate domain knowledge in a reusable library, providing abstractions for a particular domain. As such, they can form the basis for domain-specific languages, which may offer notational constructs, static analysis, and optimizations specific for the domain. Additional abstractions can be incrementally added on top of a domain-specific, following an inductive approach towards its design, evolving the language as new domain insights are acquired. A problem arises when such additions do not align well with the underlying framework. In this paper, we provide different examples of this problem and describe scenarios of dealing with it.
  • MoDELS 2008 [doi, bib, researchr, ]
    As most software artifacts, meta-models can evolve. Their evolution requires conforming models to co-evolve along with them. Coupled evolution supports this. Its applicability is not limited to the modeling domain. Other domains are for example evolving grammars or database schemas. Existing approaches to coupled evolution focus on a single, homogeneous domain. They solve the co-evolution problems locally and repeatedly. In this paper we present a systematic, heterogeneous approach to coupled evolution. It provides an automatically derived domain specific transformation language; a means of executing transformations at the top level; a derivation of the coupled bottom level transformation; and it allows for generic abstractions from elementary transformations. The feasibility of the architecture is evaluated by applying it to data model evolution.
  • ICWE 2008 [doi, bib, researchr, ]
    In this paper, we present the extension of WebDSL, a domain-specific language for web application development, with abstractions for declarative definition of access control. The extension supports the definition of a wide range of access control policies concisely and transparently as a separate concern. In addition to regulating the access to pages and actions, access control rules are used to infer navigation options not accessible to the current user, preventing the presentation of inaccessible links. The extension is an illustration of a general approach to the design of domain-specific languages for different technical domains to support separation of concerns in application development, while preserving linguistic integration. This approach is realized by means of a transformational semantics that weaves separately defined aspects into an integrated implementation.
  • WCRE 2008 [doi, bib, researchr, ]
    Domain-specific languages (DSLs) improve programmer productivity by providing high-level abstractions for the development of applications in a particular domain. However,the smaller distance to the application domain entails more frequent changes to the language. As a result, existing DSL models need to be converted to the new version. Manual conversion is tedious and error prone.This paper presents an approach to support DSL evolution by generation of convertors between DSLs. By analyzing the differences between DSL meta-models, a mapping is reverse engineered which can be used to generate reengineering tools to automatically convert models between different versions of a DSL. The approach has been implemented for the Microsoft DSL Tools infrastructure in two tools called DSLCompare and ConverterGenerator. The approach has been evaluated by means of three case studies taken from the software development practice at the company Avanade.
  • OOPSLA 2008 [pdf, doi, bib, researchr, ]
    WebDSL is a domain-specific language for the implementation of dynamic web applications with a rich datamodel. It consists of a core language with constructs to define entities, pages and business logic. Higher-level abstractions, modeling access control and workflow, are defined in a modular fashion as extensions of the core language.
  • LDTA 2008 [pdf, bib, researchr, ]
    Integrated Development Environments (IDEs) increase productivity by providing a rich user interface and rapid feedback for a specific language. Creating an editor for a specific language is not a trivial undertaking, and is a cumbersome task even when working with an extensible framework such as Eclipse. A new IBM-guided effort, the IMP framework, relieves the IDE developer from a significant portion of the required work by providing various abstractions for this. For embedded languages, such as embedded regular expressions, SQL queries, or code generation templates, its LALR parser generator falls short, however. Scannerless parsing with SGLR enables concise, modular definition of such languages. In this paper, we present an integration of SGLR into IMP, demonstrating that a scannerless parser can be successfully integrated into an IDE. Given an SDF syntax definition, the sdf2imp tool automatically generates an editor plugin based on the IMP API, complete with syntax checking, syntax highlighting, outline view, and code folding. Using declarative domain-specific languages, these services can be customized, and using the IMP metatooling framework it can be extended with other features.
  • MoDELS 2008 [doi, bib, researchr, ]
    Workflow languages are designed for the high-level description of processes and are typically not suitable for the generation of complete applications. In this paper, we present WebWorkFlow, an object-oriented workflow modeling language for the high-level description of workflows in web applications. Workflow descriptions define procedures operating on domain objects. Procedures are composed using sequential and concurrent process combinators. WebWorkFlow is an embedded language, extending WebDSL, a domain-specific language for web application development, with workflow abstractions. The extension is implemented by means of model-to-model transformations. Rather than providing an exclusive workflow language, WebWorkFlow supports interaction with the underlying WebDSL language. WebWorkFlow supports most of the basic workflow control patterns.
  • GPCE 2007 [doi, bib, researchr, ]
    Software written in one language often needs to construct sentences in another language, such as SQL queries, XML output, or shell command invocations. This is almost always done using unhygienic string manipulation, the concatenation of constants and client-supplied strings. A client can then supply specially crafted input that causes the constructed sentence to be interpreted in an unintended way, leading to an injection attack. We describe a more natural style of programming that yields code that is impervious to injections by construction. Our approach embeds the grammars of the guest languages (e.g., SQL) into that of the host language (e.g., Java) and automatically generates code that maps the embedded language to constructs in the host language that reconstruct the embedded sentences, adding escaping functions where appropriate. This approach is generic, meaning that it can be applied with relative ease to any combination of host and guest languages.
  • Model-driven software evolution: A research agenda
    Proceedings 1st International Workshop on Model-Driven Software Evolution 2007 [bib, researchr]
  • MoDELS 2007 [doi, bib, researchr, ]
    Language libraries extend regular libraries with domain-specific notation. More precisely, a language library is a combination of a domain-specific language embedded in the general-purpose host language, a regular library implementing the underlying functionality, and an assimilation transformation that maps embedded DSL fragments to host language code. While the basic architecture for realizing language libraries is the same for all applications, there are many design choices to be made in the design of a particular combination of library, guest language syntax, host language, and assimilation. In this paper, we give an overview of the design space for syntax embeddings and assimilations for the realization of language libraries.
  • Spoofax: An Interactive Development Environment for Program Transformation with Stratego/XT
    Proceedings of the Seventh Workshop on Language Descriptions, Tools and Applications (LDTA 2007) 2007 [bib, researchr]
  • GTTSE 2007 [doi, bib, researchr, ]
    The goal of domain-specific languages (DSLs) is to increase the productivity of software engineers by abstracting from low-level boil- erplate code. Introduction of DSLs in the software development process requires a smooth workflow for the production of DSLs themselves. This requires technology for designing and implementing DSLs, but also a methodology for using that technology. That is, a collection of guidelines, design patterns, and reusable DSL components that show developers how to tackle common language design and implementation issues. This paper presents a case study in domain-specific language engineering. It reports on a pro ject in which the author designed and built WebDSL, a DSL for web applications with a rich data model, using several DSLs for DSL engineering: SDF for syntax definition and Stratego/XT for code gener- ation. The paper follows the stages in the development of the DSL. The contributions of the paper are three-fold. (1) A tutorial in the application of the specific SDF and Stratego/XT technology for building DSLs. (2) A description of an incremental DSL development process. (3) A domain- specific language for web-applications with rich data models. The paper concludes with a survey of related approaches.
  • ENTCS 147(1) 2006 [doi, bib, researchr, ]
    Properties such as logging, persistence, debugging, tracing, distribution, performance monitoring and exception handling occur in most programming paradigms and are normally very difficult or even impossible to modularize with traditional modularization mechanisms because they are cross-cutting. Recently, aspect-oriented programming has enjoyed recognition as a practical solution for separating these concerns. In this paper we describe an extension to the Stratego term rewriting language for capturing such properties. We show our aspect language offers a concise, practical and adaptable solution for dealing with unanticipated algorithm extension for forward data-flow propagation and dynamic type checking of terms. We briefly discuss some of the challenges faced when designing and implementing an aspect extension for and in a rule-based term rewriting system.
  • FUIN 69(1-2) 2006 [doi, bib, researchr, ]
    The applicability of term rewriting to program transformation is limited by the lack of control over rule application and by the context-free nature of rewrite rules. The first problem is addressed by languages supporting user-definable rewriting strategies. The second problem is addressed by the extension of rewriting strategies with scoped dynamic rewrite rules. Dynamic rules are defined at run-time and can access variables available from their definition context. Rules defined within a rule scope are automatically retracted at the end of that scope. In this paper, we explore the design space of dynamic rules, and their application to transformation problems. The technique is formally defined by extending the operational semantics underlying the program transformation language Stratego, and illustrated by means of several program transformations in Stratego, including constant propagation, bound variable renaming, dead code elimination, function inlining, and function specialization.
  • GTTSE 2006 [doi, bib, researchr, ]
    General-purpose programming languages provide limited facilities for expressing domain-specific concepts in a natural manner. All domain concepts need to be captured using the same generic syntactic and semantic constructs. Generative programming methods and program transformation techniques can be used to overcome this lack of abstraction in general-purpose languages. In this tutorial we describe the MetaBorg method for embedding domain-specific languages, tailored syntactically and semantically to the application domain at hand, in a general-purpose language. MetaBorg is based on Stratego/XT, a language and toolset for the implementation of program transformation systems, which is used for the definition of syntactic embeddings and assimilation of the embedded constructs into the surrounding code. We illustrate MetaBorg with three examples. JavaSwul is a custom designed language for implementing graphical user-interfaces, which provides high-level abstractions for component composition and event-handling. JavaRegex is a new embedding of regular expression matching and string rewriting. JavaJava is an embedding of Java in Java for generating Java code. For these cases we show how Java programs in these domains become dramatically more readable, and we give an impression of the implementation of the language embeddings.
  • PEPM 2006 [doi, bib, researchr, ]
    Stratego/XT is a language and toolset for program transformation. The Stratego language provides rewrite rules for expressing basic transformations, programmable rewriting strategies for controlling the application of rules, concrete syntax for expressing the patterns of rules in the syntax of the object language, and dynamic rewrite rules for expressing context-sensitive transformations, thus supporting the development of transformation components at a high level of abstraction. The XT toolset offers a collection of flexible, reusable transformation components, as well as declarative languages for deriving new components. Complete program transformation systems are composed from these components. In this paper we give an overview of Stratego/XT 0.16.
  • OOPSLA 2006 [doi, bib, researchr, ]
    Aspect-Oriented Programming (AOP) is attracting attention from both research and industry, as illustrated by the ever-growing popularity of AspectJ, the de facto standard AOP extension of Java. From a compiler construction perspective AspectJ is interesting as it is a typical example of compositional language, ie a language composed of a number of separate languages with different syntactical styles: in addition to plain Java, AspectJ includes a language for defining pointcuts and one for defining advices. Language composition represents a non-trivial challenge for conventional parsing techniques. First, combining several languages with different lexical syntax leads to considerable complexity in the lexical states to processed. Second, as new language features for AOP are being explored, many research proposals are concerned with further extending the AspectJ language, resulting in a need for an extensible syntax definition.This paper shows how scannerless parsing elegantly addresses the issues encountered by conventional techniques when parsing AspectJ . We present the design of a modular, extensible, and formal definition of the lexical and context-free aspects of the AspectJ syntax in the Syntax Definition Formalism SDF, which is implemented by a scannerless, generalized-LR parser (SGLR). We introduce grammar mixins as a novel application of SDF's modularity features, which allows the declarative definition of different keyword policies and combination of extensions. We illustrate the modular extensibility of our definition with syntax extensions taken from current research on aspect languages. Finally, benchmarks show the reasonable performance of scannerless generalized-LR parsing for this grammar.