common-lisp RETURN子句与RETURN形式。
示例
在中LOOP，您可以(return)在任何表达式中使用CommonLisp表单，这将导致该LOOP表单立即求值为的值return。
LOOP也有一个return几乎几乎相同的子句，唯一的区别是您没有用括号将其括起来。该子句在LOOPDSL中使用，而形式在表达式中使用。
(loop for x in list
do (if (listp x) ;; Non-barewords after DO are expressions
(return :x-has-a-list)))
;; Here, both the IF and the RETURN are clauses
(loop for x in list
if (listp x) return :x-has-a-list)
;; Evaluate the RETURN expression and assign it to X...
;; except RETURN jumps out of the loop before the assignment
;; happens.
(loop for x = (return :nothing-else-happens)
do (print :this-doesnt-print))之后的东西finally必须是表达式，因此(return)必须使用形式而不是return子句：
(loop for n from 1 to 100
when (evenp n) collect n into evens
else collect n into odds
finally return (values evens odds)) ;; ERROR!
(loop for n from 1 to 100
when (evenp n) collect n into evens
else collect n into odds
finally (return (values evens odds))) ;; Correct usage.