an object.
The variables +, ++, and +++ are maintained by the Lisp read-eval-print loop to save forms that were recently evaluated.
The value of + is the last form that was evaluated, the value of ++ is the previous value of +, and +++ is the previous value of ++.
(+ 0 1)
→1
(- 4 2)
→2
(/ 9 3)
→3
(list + ++ +++)
→((/ 9 3) (- 4 2) (+ 0 1))
(defparameter *a* 1)
→*A*
(defparameter *b* 2)
→*B*
(defparameter *c* 3)
→*B*
(defparameter *d* (list *a* *b* *c*))
→*D*
(setf *a* 4 *b* 5 *c* 6 *d* (list a b c))
→(4 5 6)
(list *a* *b* *c*)
→(4 5 6)
(eval +++)
→(1 2 3)
#.`(,@++ *d*)
→(1 2 3 (1 2 3))
Variable -, Variable *, Variable/, {\secref\TopLevelLoop}
None.