anchor.diff:    (backend (middleend x)))
   
   (defun codegen-section (section data)
  -  (development-message "Codegen ~A~%" section)
  -  (with-temporary (accumulate-toplevel-expressions?) (not (accumulated-toplevel? section))
  -    (codegen data)))
  +  (development-message "Codegen ~A.~%" section)
  +  (codegen data))
   
   (defun codegen-sections (sections)
     (alet (map-sections #'codegen-section sections (cached-output-sections))
  
positive.code:   (frontend (read-file path)))
  
  (defun frontend-section (section data)
    (development-message "Frontend ~A~%" section)
    (?
      (symbol? section)  (frontend (? (function? data)
                                      (funcall data)
  
negative.code: (defun codegen-accumulated-toplevels ()
    (& (accumulate-toplevel-expressions?)
       (accumulated-toplevel-expressions)
       (with-temporaries ((sections-to-update) '(accumulated-toplevel)
                          (accumulate-toplevel-expressions?) nil)
         (quick-compile-sections (list (. 'accumulated-toplevel
                                          #'make-toplevel-function))))))
  
  