Re: Am I missing something about (loop ... maximizing ...) ?

Raffael Cavallaro wrote:
 

Indeed. Here's rob Warnock's version with the full boat of loop
keywords using triplets instead of an association list:
 
CL-USER 22 > (defun find-maximizing-item (list &key (key #'identity)
(test #'<))
               (loop for item in list
                     for value = (funcall key item)
                     and position from 0
                     for current-triplet = (list item value position)
                     as max-triplet = current-triplet
                     then (if (funcall test (second max-triplet)
(second current-triplet))
                            current-triplet
                            max-triplet)
                     finally return
                     (values (first max-triplet) (second max-triplet)
(third max-triplet))))

 
 
Rejected by ABCL:
 
Debugger invoked on condition of type PROGRAM-ERROR:

Rejected by SBCL:

;    A compound form was expected, but RETURN found.
;   current LOOP context: FINALLY RETURN (VALUES (FIRST MAX-TRIPLET)
;                                                (SECOND MAX-TRIPLET)
;                                                (THIRD MAX-TRIPLET)).

Gauche Scheme

(use srfi-1) ;; second

(define (maximizing-item the-list :key (key identity))
  (fold
    (lambda (item i best)
      (let ((value (key item)))
        (if (or (null? best) (> value (second best)))
          (list item value i)
          best)))
    '()
    the-list
    (lrange 0)))

(maximizing-item '("bells" "usher" "ullalume" "poe") :key string-length)
  ===>
("ullalume" 8 2)