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Library-based Language Extensibility

SugarJ Eclipse plugin



In essence, the goal of SugarJ is to enable expressing programs in the syntax most natural to the problem domain the program is supposed to address. For instance, when generating XML documents in Java, the programmer should be able to use standard XML syntax instead of Java syntax for calling JDOM, say.

We propose to integrate syntactic extensibility into the main extension mechanism of programming languages—libraries. Libraries thus export syntactic sugar in addition to semantic artifacts traditionally exported: classes, methods, data types, etc. When importing a library, the syntax of the general purpose language is augmented by the syntactic definition exported by the library.

SugarJ in action

Notably, libraries that contain syntactic sugar retain the composability and self-applicability of conventional libraries: syntactic sugar can be composed by importing multiple libraries; syntactic sugar can be used in the development of a library that exports syntactic sugar itself. This enables the embedding of DSLs and the development of meta-DSLs, that is a DSL for defining DSLs, without ever leaving or reasoning outside of a SugarJ program.

Installation and Usage

Please ensure enough stack space (about 4-16 MB) is available for the SDF parser. You can set the stack space of your Java runtime using the -Xss16m command line argument when starting Eclipse or setting -Xss16m in your eclipse.ini file.

For a quick start, install our Eclipse plugin available at The update dialog will let you select any number of our currently supported host languages: Java (*.sugj), Haskell (*.shs), Prolog (*.sugp).

The source code of all components of SugarJ is available on github:
case studies, compiler, IDE,

We also prepared some information on first steps with SugarJ.


We are currently developing a number of extensions of SugarJ. The relevant code can be found as follows:


Project lead: Sebastian Erdweg, TU Darmstadt

Get in touch, discuss, or simply stay up-to-date by joining the SugarJ Google group.



A Framework for Extensible Languages
Sebastian Erdweg and Felix Rieger. In Proceedings of Conference on Generative Programming: Concepts & Experiences (GPCE), pages 3–12. ACM, 2013. [ .pdf ]

Extensible Languages for Flexible and Principled Domain Abstraction
Sebastian Erdweg. PhD thesis, Philipps-Universität Marburg, 2013. [ .pdf ]

Embedding a Questionnaire DSL with SugarJ
Sebastian Erdweg. In Proceedings of Language Workbench Challenge (LWC), 2013. [ pdf ]

Layout-sensitive Language Extensibility with SugarHaskell
Sebastian Erdweg, Felix Rieger, Tillmann Rendel, and Klaus Ostermann. In Proceedings of Haskell Symposium, pages 149-160. ACM, 2012. [ .pdf ]

Language Composition Untangled
Sebastian Erdweg, Paolo G. Giarrusso, and Tillmann Rendel. In Proceedings of Workshop on Language Descriptions, Tools and Applications (LDTA), 7:1-7:8. ACM, 2012. [ .pdf ]

Growing a Language Environment with Editor Libraries
Sebastian Erdweg and Lennart C. L. Kats and Tillmann Rendel and Christian Kästner and Klaus Ostermann and Eelco Visser. In Proceedings of Conference on Generative Programming and Component Engineering (GPCE), pages 167–176. ACM, 2011. [ .pdf ]

SugarJ: Library-based Syntactic Language Extensibility
Sebastian Erdweg, Tillmann Rendel, Christian Kästner and Klaus Ostermann. In Proceedings of Conference on Object-Oriented Programming, Systems, Languages, and Applications (OOPSLA), pages 391–406. ACM, 2011. Distinguished Paper Award. [ .pdf ]