1. IMDEA Software Institute, Madrid, Spain. E-mails: gilles.barthe@imdea.org, federico.olmedo@imdea.org
2. INRIA – Méditerranée, Sophia Antipolis, France. E-mails: benjamin.gregoire@inria.fr, sylvain.heraud@gmail.com
3. Microsoft Research, Cambridge, UK. E-mail: santiago@microsoft.com