MDL (the MIT Design Language) is a descendant of the
Lisp programming language. Its initial purpose was to provide high level language support for the Dynamic Modeling Group at
MIT's
Project MAC. It was initially developed in 1971 on the
PDP-10 computer under the
Incompatible Timesharing System. The initial development team consisted of
Gerald Sussman and
Carl Hewitt of the Artificial Intelligence Lab, and Chris Reeve,
Bruce Daniels, and David Cressey of the Dynamic Modeling Group. Later, Stu Galley, also of the Dynamic Modeling Group, wrote the MDL documentation.