William Cook passed away on Wed. Much of 1990s OOP was defined by his seminal papers. When he returned after a decade in industry (AppleScript!) I invited him to @BrownCSDept (where he got his PhD from Peter Wegner) and we became friends. Tragic. -- @ShriramKMurthi
His essay on ADTs and objects from 2009 is the best explanation of the topic I have ever seen. A classic. -- @Gilad_Bracha