nth-value
n form ⇒ object
n | a non-negative integer; evaluated. |
form | a form; evaluated as described below. |
object | an object. |
Evaluates n and then form,
returning as its only value the nth value yielded by form,
or nil if n is greater than or equal to the number of values
returned by form. (The first returned value is numbered 0
.)
(nth-value 0 (values 'a 'b)) ⇒ A
(nth-value 1 (values 'a 'b)) ⇒ B
(nth-value 2 (values 'a 'b)) ⇒ NIL
(let* ((x 83927472397238947423879243432432432)
(y 32423489732)
(a (nth-value 1 (floor x y)))
(b (mod x y)))
(values a b (= a b)))
⇒ 3332987528, 3332987528, true
Operationally, the following relationship is true, although nth-value might be more efficient in some implementations because, for example, some consing might be avoided.
(nth-value n form) ≡ (nth n (multiple-value-list form))