anchor.diff:                                       table))
                         tables)
                    (let ((vector (coerce (shiftf vector nil) 'simple-vector)))
  +                   (declare (type (simple-array cons 1) vector))
                      (parallel:dotimes (i (length vector)
  -                                        (if master-table
  -                                            (values vector
  -                                                    (clean-table master))
  -                                            vector))
  +                                        (values vector (clean-table master)))
                        (let* ((cache  (aref vector i))
                               (values (cdr cache)))
                          (setf (cdr cache) (reduce reduce values))))))))
  
positive.code:     (declare (type (simple-array hash-table 1) tables))
      (labels ((clean-table (table)
                 (declare (type hash-table table))
                 (maphash (lambda (k v)
                            (setf (gethash k table) (cdr v)))
                          table)
                 table)
               (aggregate-keys ()
                 (let* ((size   (reduce #'max tables :key #'hash-table-count))
                        (master (make-hash-table :test group-test :size size))
  
negative.code:            "MAP-GROUP-REDUCE"))
  
  (defpackage "PARALLEL-IMPL"
    (:use "CL" "SB-EXT")
    (:import-from "PARALLEL" "PROMISE" "PROMISE-VALUE"
                  "FUTURE" "FUTURE-VALUE"))
  
  