anchor.diff:  ;;; pattern glue
   
   (defun make-default-event ()
  +  "Get `*event*' if it's not nil, or get a fresh empty event."
     (or *event* (event)))
   
   (defun set-parents (pattern)
  
positive.code: (defpattern ps (pattern)
    (pattern
     pstream)
    :documentation "Defines a pattern whose pstream will be preserved to subsequent calls to `as-pstream'. To reset the pstream, simply re-evaluate the ps definition.
  
  Based on the pattern originally from the miSCellaneous SuperCollider library.
  
  Example:
  
  ;; (defparameter pst (ps (pseries)))
  ;;
  ;; (next-upto-n pst 4)
  ;; ;=> (0 1 2 3)
  ;;
  ;; (next-upto-n pst 4)
  ;; ;=> (4 5 6 7)
  ;;
  ;; (defparameter pst (ps (pseries)))
  ;;
  ;; (next-upto-n pst 4)
  ;; ;=> (0 1 2 3)
  
  See also: `pdef'"
  
negative.code:   (typep object 'pattern))
  
  (defun all-patterns ()
    "Get a list of the names of all defined pattern classes.
  
  See also: `all-pdefs'"
    *patterns*)
  