anchor.diff:  ++++++++>-]<++++.------------.---.>+++++++[<---------->-]<+.
   >++++++++[<+++++++++++>-]<-.>++[<----------->-]<.+++++++++++
   ..>+++++++++[<---------->-]<-----.---.+++.---.[-]<<<]")
  +
  +;;;;
  +;; eval functions
  +;;;;
  +
   
   (defstruct bf-state
     (mem (make-array 30000 :element-type '(unsigned-byte 8) :initial-element 0))
  
positive.code:                       (incf ip)))
               (otherwise (incf ip)))))))
  
  (defun bf-body (program)
    `(lambda ()
       (let ((ptr 0) (mem (make-array 30000 :element-type '(unsigned-byte 8) :initial-element 0)))
  
negative.code: 
  (defun bf-compile (program)
    (time (compile nil (bf-body program))))
  