go

go Special Operator

Syntax:

go tag →

Arguments and Values:

tag—a 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 Section 5.2 (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

Expanded Reference: go

tip

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(go )