anchor.diff:  
   (declaim (inline checkpoint))
   (defun checkpoint (ctx)
  -  (vector-push-extend (parser-context-cursor ctx) (parser-context-checkpoints ctx)))
  +  (push (parser-context-cursor ctx) (parser-context-checkpoints ctx)))
   
   (declaim (inline rollback))
   (defun rollback (ctx)
  -  (setf (parser-context-cursor ctx) (vector-pop (parser-context-checkpoints ctx))))
  +  (setf (parser-context-cursor ctx) (pop (parser-context-checkpoints ctx))))
   
   (declaim (inline commit))
   (defun commit (ctx)
  -  (vector-pop (parser-context-checkpoints ctx)))
  +  (pop (parser-context-checkpoints ctx)))
   
   
   ;;; Atom, Rule & Type Matching
  
positive.code:   (data nil :read-only t :type string)
    (size nil :read-only t :type unsigned-byte)
    (cursor 0 :type unsigned-byte)
    (checkpoints
     (make-array 8 :element-type 'unsigned-byte :adjustable t :fill-pointer 0)
     :type (vector unsigned-byte *))
    attachment)
  
  (defgeneric create-parser-context (input &rest args))
  
negative.code: 
  
  ;;; Grammar Compiler
  
  (define-condition parser-return ()
    ((value :initarg :value :accessor parser-return-value)))
  
  (defun compile-grammar (ctx form)
    (labels ((compile-exprs (form &optional (in-meta t))
  