VL-Eli: A Generator for Visual Languages

Visual languages play an important role in modelling systems, in speci cation of software, and in speci c application domains. A processor for a visual language consists of a graphical frontend attached to phases that analyse and transform visual programs. Therefore, the construction of a visual language processor requires a wide range of conceptual and technical knowledge: from issues of visual design and graphical implementation to aspects of analysis and transformation for languages in general. We present the tool VL-Eli [1,2,3], that incorporates such knowledge. VL-Eli generates structure editors from high level speci cations. A visual language is speci ed by identifying certain patterns in the language structure and selecting a visual representation from a set of precoined solutions. For example, states in UML statechart diagrams are arranged according to the Set pattern: They are an unordered collection of elements, which can be placed at arbitrary positions in a two-dimensional region. The language developer selects a precoined speci cation module for Set representations and parameterizes the details of the representation by a variety of options. Visual programs are represented by attributed abstract trees. Therefore, further phases of processing can be generated by state-of-the-art tools for language implementation [4]. We demonstrate that ambitious visual languages can be implemented with reasonable small e ort and with rather limited technical knowledge. The approach is suitable for a large variety of visual language