25.2.21 +, ++, +++ [Variable]

Value Type::

an object.

Initial Value::

implementation-dependent.

Description::

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 the value of +++ is the previous value of ++.

Examples::

(+ 0 1) ⇒  1
(- 4 2) ⇒  2
(/ 9 3) ⇒  3
(list + ++ +++) ⇒  ((/ 9 3) (- 4 2) (+ 0 1))
(setq a 1 b 2 c 3 d (list a b c)) ⇒  (1 2 3)
(setq 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))

Affected By::

Lisp read-eval-print loop.

See Also::

- (variable), * (variable), / (variable), Top level loop