[racket] translate from Racket to Common Lisp

What Matthew and everyone else said is critical. Read those 
before reading on. Also consider using optimizations in Racket
or converting to TR and asking for fixed-point numbers. 

;; --- 

However, we do understand the need for running programs in both worlds
(Racke and CL). An alternative is to write a program so that it basically 
ports itself (with a few tweaks). 

For years, Dorai Sitaram maintained a macro/constraint set for just 
this purpose. The idea is written down in a short Scheme Workshop
paper: 

  http://repository.readscheme.org/ftp/papers/sw2003/Scmxlate.pdf

Producing a #lang cl/port for this purpose would be a 'good thing'.
Others may benefit too. You could contribute it to Planet. 

-- Matthias



On Nov 4, 2012, at 8:20 AM, Matthew Flatt wrote:

> At Fri, 2 Nov 2012 16:25:09 +0000 (UTC), daniel rupistraliz avez wrote:
>>  One motivation is speed, for example a recent example in the racket blog about
>> the 2n+1 problem gives 1200 milliseconds in Racket and 500 in sbcl (without
>> declaring fixnum or any other optimization).
> 
> Although it's not really your question, I'm generally interested in
> understanding performance differences. Can you tell me more about what
> you're measuring, and maybe provide the SBCL version of the code that
> you're using?
> 
> 
> If I take Danny's code form the blog and just try
> 
>  time racket three-n-plus-one.rkt < sample-data.txt
> 
> on the command line, it takes 720 millisecond on my machine, but
> essentially all of that time is loading and compiling the code.
> Wrapping `time' around the body of the `main' submodule shows that the
> actual computation takes only 2 milliseconds.
> 
> If I try
> 
> raco make three-n-plus-one.rkt 
> time racket three-n-plus-one.rkt < sample-data.txt
> 
> then the overall time drops down to 264 milliseconds. Some other
> changes can reduce the start-up time further, but I don't know if this
> is at all related the way you're measuring performance.
> 
> So, I wonder whether you're using different inputs and how you're
> measuring the run time.
> 
> Thanks!
> 
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