anchor.diff:  
   ;;;; Initialization
   
  +;;; For some reason, PAPI really only likes to be loaded once.
  +(unless (foreign-symbol-pointer "PAPI_num_counters")
  +  (load-foreign-library '(:or "libpapi.so.3" "libpapi.so")))
  +
   (defconstant +papi-not-inited+ 0)
   
   (defcfun "PAPI_is_initialized" :int)
  
positive.code:                         :available t
                          :native nil
                          :papi nil)))
  
  ;;; For some reason, PAPI really only likes to be loaded once.
  (when (zerop (hash-table-count *events*))
    (load-foreign-library '(:or "libpapi.so.3" "libpapi.so"))
    (push-all-events-to-hash-table *events*))
  
  (defun list-event-names ()
    (loop for event being the hash-keys of *events* collect event))
  
negative.code: ;;;; -*- coding: utf-8; indent-tabs-mode: nil -*-
  
  (defpackage #:perfpiece
    (:use #:cl #:cffi)
    (:import-from #:alexandria
                  #:make-keyword #:switch #:when-let #:with-unique-names
                  #:symbolicate #:mean #:standard-deviation #:once-only))
  
  (in-package #:perfpiece)
  
  ;;;; Errors
  