|MDL - (Originally "Muddle"). C. Reeve, Carl Hewitt and Gerald Sussman, Dynamic Modeling Group, MIT ca. 1971. Intended as a
successor to Lisp, and a possible base for Planner-70.
Basically LISP 1.5 with data types and arrays. Many of its
features were advanced at the time (I/O, interrupt handling
and coroutining), and were incorporated into later LISP
dialects ("optional", "rest" and "aux" markers). In the mid
80's there was an effort to use bytecoding to make the
language portable. CLU was first implemented in MDL. Infocom
wrote Zork in MDL, and used it as the basis for the ZIL
Implementations exist for ITS, TOPS-20, BSD 4.3, Apollo Domain, SunOS and A/UX.
["The MDL Programming Language", S.W. Galley et al, Doc SYS.11.01, Project MAC, MIT (Nov 1975)].