common-lisp Functions RETURN-FROM, exit from a block or a function
Example
Functions always establish a block around the body. This block has the same name as the function name. This means you can use RETURN-FROM with this block name to return from the function and return values.
You should avoid returning early whenever possible.
(defun foobar (x y)
(when (oddp x)
(format t "X (~d) is odd. Returning immediately.~%" x)
(return-from foobar "return value"))
(format t "X: ~s~@
Y: ~s~%"
x y))
(foobar 10 20)
; X: 10
; Y: 20
;=> NIL
(foobar 9 20)
; X (9) is odd. Returning immediately.
;=> "return value"
