anchor.diff:                                      (nsubseq seq start end)
                                       count
                                       from-end)))
  -        (if (listp seq)
  -            items
  -            ;; Return a sequence that is "like" the original.
  -            (replace (subseq seq 0 (length items)) items)))))
  +        (make-sequence-like seq (length items) :initial-contents items))))
   
   (assert (equal '(0 2 4 6 8) (filter #'evenp (iota 100) :count 5)))
  +(assert (equalp #(0 2 4 6 8) (filter #'evenp (coerce (iota 100) 'vector) :count 5)))
   (assert (equal '(90 92 94 96 98)
                  (filter #'evenp (iota 100) :count 5 :from-end t)))
   
  
positive.code: The name is from Arc."
    (declare (array-length n))
    (cond ((= n 0)
           (coerce-by-example '() seq))
          ((= n 1)
           (coerce-by-example (list (extremum seq pred :key key)) seq))
          ((length<= seq n)
           (sort (copy-seq seq) pred :key key))
          (t (fbind ((key (if memo
  
negative.code:                                (heap-insert heap elt :key key :test #'test))))
                        (incf i))
                      seq)
                 (let ((bestn (take n (nreverse (heap-extract-all heap :key key :test #'test)))))
                   (make-sequence-like seq n :initial-contents bestn)))))))
  
  (dotimes (i 100)
    (let ((list (map-into (make-list 1000) (lambda () (random 1000)))))
  