For the participants of our hands-on tutorial on Creating DSLs with Stratego/XT at the Code Generation 2009 conference, we (i.e. Rob Vermaas) created a VirtualBox image with all the software needed during the tutorial. In particular, it contains a full installation of Stratego/XT with compiler, libraries, and auxiliary packages such as java-front. In addition, the image contains a built-from-source installation of the WebDSL language for building web applications, and an installation of tomcat for deploying created web apps.

The image and instructions for its installation are available from

During the tutorial additional material will be handed out with concrete exercises.

The virtual machine is also useful for exploring Stratego/XT and WebDSL outside the context of this particular tutorial.

Spoofax/IMP is a toolset for the creation of interactive development environments for custom languages based on domain-specific languages for editor services. The toolset is especially aimed at the developers of domain-specific languages, allowing them to provide IDE support for their specialist language under development. An important feature of Spoofax/IMP is the support for language composition, i.e. for languages consisting of multiple, syntactically different, sub-languages. Furthermore, the toolset allows the customization of heuristically generated editor services without loosing the ability to regenerate these services when a language evolves.

At LDTA 2009 we presented a paper about Spoofax/IMP. The final version of that paper is now finished, and a pre-print is available.

L. C. L. Kats, K. T. Kalleberg, and E. Visser. Domain-Specific Languages for Composable Editor Plugins. In T. Ekman and J. Vinju, editors, Proceedings of the Ninth Workshop on Language Descriptions, Tools, and Applications (LDTA 2009), Electronic Notes in Theoretical Computer Science. Elsevier Science Publishers, April 2009. [pdf]

Abstract: 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.

We just got the notification that our submission to OOPSLA 2009 has been accepted. The paper presents a solution to error recovery for the SGLR parsing algorithm. Here’s the full citation and abstract (pre-print will follow later):

Lennart C. L. Kats, Maartje de Jonge, Emma Nilsson-Nyman, and Eelco Visser. “Providing Rapid Feedback in Generated Modular Language Environments. Adding Error Recovery to Scannerless Generalized-LR Parsing” In Gary T. Leavens, editor, Proceedings of the 24th ACM SIGPLAN Conference on Object-Oriented Programing, Systems, Languages, and Applications (OOPSLA 2009), New York, NY, USA, October 2009. ACM. (to appear).

Abstract: 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 automatically generate new productions for existing grammars, making them more permissive of their inputs. 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.

I have been playing around for a couple of minutes with yUML, an online service by Tobin Harris for creating UML diagrams using a textual input language. The diagram below is generated while you load this page. The input needed to generate the diagram is the following list of relations:

  [Book]<->*[InCollection] .

This diagram documents a (small) subset of the data model underlying the application for bibliography sharing and reviewing.


I have been invited to give a talk at the Sixth International Workshop on Web Information Systems Modeling (WISM 2009), which will be held in June in Amsterdam (co-located with CAiSE 2009). Here’s the abstract I wrote for the talk.

Abstract In this talk I give an overview of the design and application of WebDSL, a domain-specific language for data centric web applications. WebDSL linguistically integrates the definition of data models, user interfaces, actions, access control rules, data validation rules, styling rules, and workflow definitions. While maintaining separation between these concerns through specialized sub-languages, linguistic integration ensures static consistency checking and correct code generation. The language allows developers to concentrate on the essential design of web applications, abstracting from accidental complexity, such as the details of data persistence. The combination of high-level and low-level constructs ensures high expressivity, while supporting customization to application requirements. The application of WebDSL is illustrated using the application for bibliography sharing and reviewing.