Generative and Transformational Techniques in Software Engineering IV : International Summer School, GTTSE 2011, Braga, Portugal, July 3-9, 2011, Revised and Extended Papers - Lämmel, Ralf (Herausgeber); Saraiva, João (Herausgeber); Visser, Joost (Herausgeber) (Programming and Software Engineering, 2013)