I don't see DEFUN in a ~1966 copy of PDP-6 LISP. I do see it in a 1972 Maclisp.
AI memo 116A from 1967 doesn't have DEFUN. (It does have MACRO.)
Retrocomputing Stack Exchange is a question and answer site for vintage-computer hobbyists interested in restoring, preserving, and using the classic computer and gaming systems of yesteryear. It only takes a minute to sign up.Sign up to join this community
From the MIT AI Lab file .INFO.; LISP ARCHIV for Maclisp updates:
3/1/69 JONL THE CURRENT VERSION OF LISP, "LISP 102", HAS THE FOLLOWING AS-YET UNDOCUMENTED FEATURES: 1)"DEFUN" IS AN FSUBR USED TO DEFINE FUNCTIONS. EXAMPLES ARE (DEFUN ONECONS (X) (CONS 1 X)) WHICH IS EQUIVALENT TO (DEFPROP ONECONS (LAMBDA (X) (CONS 1 X) EXPR) AND (DEFUN SMASH FEXPR (L) (RPLACD L NIL)) IS EQUIVALENT TO (DEFPROP SMASH (LAMBDA (L) (RPLACD L NIL)) FEXPR) THE NOVEL FEATURE OF "DEFUN" IS THAT ONE NEED NOT BE SO CONCERNED WITH BALANCING PARENTHESES AT THE VERY END OF THE FUNCTION DEFINITION, SINCE THE TYPE FLAG MAY BE OMITTED IF IT IS "EXPR", AND APPEARS NEAR THE FRONT OF THE "DEFUN" LIST IF IT IS SOME OTHER. ALSO, THE "LAMBDA" NEED NOT BE DIRECTLY INSERTED.