MacLisp <language> A dialect of {Lisp} developed at {MIT} AI Lab in 1966, known for its efficiency and programming facilities. MacLisp was later used by {Project MAC}, {Mathlab} and {Macsyma}. It ran on the {PDP-10}. It introduced the {LEXPR} (a function with variable {arity}), {macros}, {arrays}, and {CATCH/THROW}. MacLisp was one of two main branches of LISP (the other being {Interlisp}). In 1981 {Common LISP} was begun in an effort to combine the best features of both. ["MACLISP Reference Manual", D.A. Moon <[email protected]>, TR Project MAC, MIT 1974]. (2004-05-07)