CLCS
src report error
Index
catch Data and Control Flow Dictionary return-from
Special Operator

go

go tag ⇒ #<NoValue>

Arguments and Values

taga go tag.

Description

go transfers control to the point in the body of an enclosing tagbody form labeled by a tag eql to tag. If there is no such tag in the body, the bodies of lexically containing tagbody forms (if any) are examined as well. If several tags are eql to tag, control is transferred to whichever matching tag is contained in the innermost tagbody form that contains the go. The consequences are undefined if there is no matching tag lexically visible to the point of the go.

The transfer of control initiated by go is performed as described in Transfer of Control to an Exit Point.

Examples

 (tagbody
   (setq val 2)
   (go lp)
   (incf val 3)
   lp (incf val 4)) ⇒  NIL
 val ⇒  6

The following is in error because there is a normal exit of the tagbody before the go is executed. 

 (let ((a nil)) 
   (tagbody t (setq a #'(lambda () (go t))))
   (funcall a))

The following is in error because the tagbody is passed over before the go form is executed. 

 (funcall (block nil
            (tagbody a (return #'(lambda () (go a))))))

See Also

tagbody

Backlinks

Condition System Concepts, control-error, Data and Control Flow Dictionary, do, do*, dolist, dotimes, Initial and Final Execution, loop, Order of Execution, prog, prog*, Simple Loop, Special Forms, Symbols in the COMMON-LISP Package, tagbody, Transfer of Control to an Exit Point, unwind-protect