I am senior researcher in the Software Analysis and Transformation (SWAT) Team at the Centrum Wiskunde & Informatica (CWI), the Dutch national research institute for mathematics and computer science. I also hold a part-time appointment as professor at the University of Groningen. My work is focused on improving the construction and deployment of Domain-Specific Languages (DSLs), programming languages, and Model-Driven Development (MDD), to address software engineering challenges. Together with Paul Klint and Jurgen Vinju I am one of the designers of Rascal, a domain specific language for meta programming. I am also working together with William Cook on a model-driven programming framework, called Ensō.