“Interlisp is a software development environment, originating from Xerox PARC in the 1970s and 1980s. supporting software research in AI, computational linguistics, graphical user interfaces, hypertext, and other research areas. Software development in Interlisp-D is a different experience than is common, even today. The features of structure editing, source code management, code analysis and cross-referencing combined to support rapid incremental development. The 1992 ACM Software System Award was awarded to the Interlisp system for pioneering work in programming environments.”
A very poignant quote from there:
We have ended up in a world where UNIX and Windows have taken over, and most people have never experienced anything else. Over the years, though, many other system designs have come and gone, and some of those systems have had neat ideas that were nevertheless not enough to achieve commercial success. We will take you on a tour of a variety of those systems, talking about what makes them special.