Re: So, what the heck is a continuation anyway?

[Guy Steele - Sun Microsystems Labs <address@hidden>]

I had a bug in three lines of @apply where it was
failing to obey the invariant that every @-routine
finished by calling either "cont" or another @-routine.
The code should read:



(defun @apply (fn args cont)
  (cond ((eq fn '+) (funcall cont (+ (first args) (second args))))
	((eq fn '*) (funcall cont (* (first args) (second args))))
	((eq fn 'call/cc)
	 (@apply (first args) (list (list 'CONTINUATION cont)) cont))
	((atom fn) (funcall cont 'UNDEFINED-FUNCTION))
	((eq (first fn) 'CLOSURE)
	 (@eval (third fn) (pairlis (second fn) args (fourth fn)) cont))
	((eq (first fn) 'CONTINUATION)
	 (funcall (second fn) (first args)))
	(t (funcall cont 'UNDEFINED-FUNCTION))))

Sorry about that.  My too-simple tests had missed this.
(See what a good thing invariants are?  :-)

--Guy