+, ++, +++ (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:

- (Function) (variable), * (Function) (variable), / (Function) (variable), Section 25.1.1 (Top level loop)