Hello! I'm trying to learn category theory and understand its links to computer science. One of my big questions is: Is category theory a wonderful specification language, or is there any executable stuff in it ? All I've seen about application until now is specification or semantics (which is already a lot!) but I wonder if anything else was ever done. Thank you for any direct answer or any pointer to good texts about this. Matthieu Amiguet IIIA University of Neuch�tel (Switzerland)