[racket] translate from Racket to Common Lisp

I tried using the type `(Fixnum -> Fixnum)', but there's a
multiplication in the function.

At Sun, 4 Nov 2012 20:42:48 -0500, Matthias Felleisen wrote:
> 
> Hmph. I would expect TR to perform as fast as 'unsafe'.
> 
> 
> On Nov 4, 2012, at 7:40 PM, Matthew Flatt wrote:
> 
> > 2668 msecs when I declare `cycle-length' as `(Integer -> Integer)' and
> > change `(even? n)' to `else', or 2809 msecs if I add `[else 0]' instead
> > of changing `(even? n)'.
> > 
> > At Sun, 4 Nov 2012 18:30:21 -0600, Robby Findler wrote:
> >> And just to complete the list, how does the TR version fare?
> >> 
> >> Robby
> >> 
> >> On Sun, Nov 4, 2012 at 6:26 PM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> >>> Thanks!
> >>> 
> >>> Sometimes, a x3 difference means that we're missing a straightforward
> >>> opportunity in performance, and that was the case here. The Racket
> >>> program spent most of its time in generic `/' by pessimistically
> >>> expecting a non-integer result.
> >>> 
> >>> I've adjusted the JIT to optimistically compute and check a fixnum
> >>> result for a division of fixnums, and then the example runs about four
> >>> times as fast on my machine:
> >>> 
> >>> Old Racket:                12589 msec
> >>> New Racket:                 3850 msec
> >>> Racket with `quotient':     3851 msec  [old or new is the same]
> >>> SBCL:                       5553 msec
> >>> SBCL, unsafe fixnum:        2692 msec
> >>> New Racket, in module:      2823 msec
> >>> Racket, unsafe fixnum:      2405 msec  [uses `fxquotient']
> >>> 
> >>> At Sun, 4 Nov 2012 15:54:51 +0000 (UTC), daniel rupistraliz wrote:
> >>>> 
> >>>> 
> >>>> racket:
> >>>> Welcome to Racket v5.2.1.
> >>>>> (define (cycle-length n)
> >>>>    (cond
> >>>>      [(= n 1)
> >>>>       1]
> >>>>      [(odd? n)
> >>>>       (add1 (cycle-length (add1 (* 3 n))))]
> >>>>      [(even? n)
> >>>>       (add1 (cycle-length (/ n 2)))]))
> >>>> 
> >>>> (time (for ([i (in-range 1 1000000)])
> >>>>          (cycle-length i)))
> >>>>> 
> >>>> cpu time: 15016 real time: 15018 gc time: 0
> >>>> 
> >>>> sbcl:
> >>>> 
> >>>> (defun cycle-length(n)
> >>>> (cond ((= n 1) 1)
> >>>>       ((oddp n) (1+ (cycle-length (1+ (* 3 n)))))
> >>>>       ((evenp n) (1+ (cycle-length (/ n 2))))))
> >>>> 
> >>>> 
> >>>> * (time (loop for i from 1 to 1000000 do (cycle-length i)))
> >>>> 
> >>>> Evaluation took:
> >>>>  6.192 seconds of real time
> >>>>  6.192387 seconds of total run time (6.192387 user, 0.000000 system)
> >>>>  100.00% CPU
> >>>>  14,496,643,427 processor cycles
> >>>>  0 bytes consed
> >>>> 
> >>>> 
> >>>> With optimizations:
> >>>> 
> >>>> (defun cycle-length(n)
> >>>>  (declare (fixnum n)
> >>>>         (ftype (function (fixnum) fixnum) cycle-length)
> >>>>         (optimize (speed 3) (safety 0) (compilation-speed 0)))
> >>>>  (cond ((= n 1) 1)
> >>>>      ((oddp n) (the fixnum (1+ (cycle-length
> >>>>                                 (the fixnum (1+ (the fixnum (* 3 n))))))))
> >>>>      ((evenp n) (cycle-length (the fixnum (/ n 2))))))
> >>>> 
> >>>> CL-USER> (time (loop for i from 1 to (expt 10 6) do (cycle-length i)))
> >>>> Evaluation took:
> >>>>  3.515 seconds of real time
> >>>>  3.524220 seconds of total run time (3.524220 user, 0.000000 system)
> >>>>  100.26% CPU
> >>>>  8,228,949,701 processor cycles
> >>>>  33,008 bytes consed
> >>>> 
> >>>> So racket = 15 seconds
> >>>>    sbcl  =  6 seconds
> >>>> sbcl optimized = 3.5 seconds.
> >>>> 
> >>>> 
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