4 Th European Lisp Symposium Special Focus on Parallelism and Efficiency Preface Message from the Programme Chair

In the recent years, all major academic events have suffered from a decreasing level of attendance and contribution, Lisp being no exception to the rule. Organizing ELS 2011 in this context was hence a challenge of its own, and I'm particularly happy that we have succeeded again. For the first time this year, we had a " special focus " on parallelism and efficiency, all very important matters for our community with the advent of multi-core programming. It appears that this calling has been largely heard, as half of the submissions were along these lines. Another notable aspect of this year's occurrence is the fact that four dialects of Lisp are represented: Common Lisp, Scheme, Racket and Clojure. This indicates that ELS is successful in attempting to gather all crowds around Lisp " the idea " rather than around Lisp " one particular language ". The European Lisp Symposium is also more European than ever, and in fact, more international than ever, with people coming not only from western Europe and the U.S.A., but also from such countries as Croatia and Bulgaria. While attending the symposium is just seeing the tip of the iceberg, a lot have happened underwater. First of all, ELS 2011 would not have been possible without the submissions we got from the authors and the careful reviews provided by the programme committee members; I wish to thank them for that. I am also indebted to the keynote speakers who have agreed to come and spread the good word. I wish to express my utmost gratitude to our sponsors who contributed to making the event quite affordable this year again. Ralf Möller was our local chair, the " Grey Eminence " of the symposium, and we owe him a lot. Finally, my thanks go to Edgar Gonçalves for taking care of the website with such reactivity and attentiveness.