anchor.diff:  (defmethod list-packages ((manager (eql :guix)))
     (mapcar #'database-entry->guix-package (guix-database)))
   
  -(defmethod refresh ((manager (eql :guix)))
  +(defmethod refresh ((manager (eql :guix))) ; TODO: Unused?
     (declare (ignore manager))
     (setf *guix-database* nil))
   
  
positive.code:      (guix utils)
       (gnu packages))
  
     ;; TODO: Use upstream's way to find packages.
     '(define (find-package name)
       (let ((result '\#f))
         (fold-packages
          (lambda (package count)
            (when (string=? (package-name package)
                            name)
              (set! result package))
            (+ 1 count))
          1)
         result))
  
     '(define* (package-output-paths package)
       "Return store items, even if not present locally."
  
negative.code:                         :output '(:string :stripped t)
                          :error-output :output))))
  
  (defvar %find-package
    ;; TODO: Use upstream's way to find packages.
    '(lamdbda (name)
      (let ((result (list)))
        (fold-packages
         (lambda (package count)
           (when (string=? (package-name package)
                           name)
             (set! result package))
           (+ 1 count))
         1)
        result)))
  
  (defun package-output-paths (name)
    "Computing the output-paths in `generate-database' is too slow, so we do it just-in-time instead."
    (guix-eval
  