From: Wang Yin
Subject: What kind of type declaration can speed up LISP code?
Date: Sun, 02 Nov 2003 14:41:57 +0000
Message-ID: <m34qxmbznu.fsf@wangyin.com>

Hi, 

I wonder what kind of type declaration can speed up LISP code.

If I declare a struct coord to use double-float vectors to represent a
coordinate this certainly can speed up the code and tell the compiler
to do floating point arithmetic.

(defstruct (coord (:constructor %make-coord))
  (vec '#(0.0d0 0.0d0) :type (vector double-float)))


But later if I declare a node structure as follows:

(defstruct (node (:print-function print-node))
  (number 0 :type fixnum)
  (degree 0 :type fixnum)
  (coord nil)
  (coord2 nil)
  (inact nil)
  )


And I define a function to operation on node structure:

(defun make-edge-connects (n1 n2 &optional (number 0))
  "Create an edge connecting node n1 and n2."

  (declare (type node n1 n2) (type fixnum number))
  (let ((new-edge (make-edge :number number
                             :vertices (list n1 n2))))
      (add-edge-to-node n1 new-edge)
      (add-edge-to-node n2 new-edge)
      new-edge))


Will the declaration of (type node n1 n2) take effect to speed up the
code? Will declaration of user defined types of function parameters
speed up the code?

Thanks.


-- 
Yin Wang,
EDA Lab,
Deparment of Computer Science and Technology,
Tsinghua University,
100084
Beijing China

From: Marco Antoniotti
Subject: Re: What kind of type declaration can speed up LISP code?
Date: Mon, 03 Nov 2003 14:32:08 +0000
Message-ID: <JFtpb.119$KR3.46355@typhoon.nyu.edu>

Wang Yin wrote:
> Hi, 
> 
> I wonder what kind of type declaration can speed up LISP code.
> 
> If I declare a struct coord to use double-float vectors to represent a
> coordinate this certainly can speed up the code and tell the compiler
> to do floating point arithmetic.
> 
> (defstruct (coord (:constructor %make-coord))
>   (vec '#(0.0d0 0.0d0) :type (vector double-float)))

Why not

	(defstruct coord
	  (x 0.0d0 :type double-float)
	  (y 0.0d0 :type double-float))
?

Or even

	(deftype coord () '(array double-float (2)))
?

Or even

	(deftype coord () 'complex)

?


> 
> 
> But later if I declare a node structure as follows:
> 
> (defstruct (node (:print-function print-node))
>   (number 0 :type fixnum)
>   (degree 0 :type fixnum)
>   (coord nil)
>   (coord2 nil)
>   (inact nil)
>   )
> 
> 
> And I define a function to operation on node structure:
> 
> (defun make-edge-connects (n1 n2 &optional (number 0))
>   "Create an edge connecting node n1 and n2."
> 
>   (declare (type node n1 n2) (type fixnum number))
>   (let ((new-edge (make-edge :number number
>                              :vertices (list n1 n2))))
>       (add-edge-to-node n1 new-edge)
>       (add-edge-to-node n2 new-edge)
>       new-edge))
> 
> 
> Will the declaration of (type node n1 n2) take effect to speed up the
> code? Will declaration of user defined types of function parameters
> speed up the code?

That depends on the implementation.  CMUCL/SBCL and the commercial 
implementations are pretty good at it. As per your function, it does not 
seem it would help much anyway.  The ADD-EDGE-TO-NODE function may do 
something slow.




Cheers
--
Marco