[plt-scheme] Re: Using PLT Scheme libs elsewhere?

From: Jens Axel Søgaard (jensaxel at soegaard.net)
Date: Fri May 18 04:18:15 EDT 2007


SpinyNorman wrote:

>Share?  I'm flattered.  Here it is, and my only claim at this point is
>that hey, it works.  Algorithmic insights are more than welcome.
>(require (lib "md5.ss"))
This md5.ss implements MD5 in Scheme. The Java MD5 is probably 
implemented in C.
So if you switch to a C-based MD5 implementation, you'll get a speedup. 
Here is
what to do:

(require (planet "digest.ss" ("soegaard" "digest.plt" 1 2)))
(require mzscheme)

(define test-string (make-string 10000))

(define (md-file-chunks port chunk-size)
  (let loop ()
      (display (md5 (read-bytes chunk-size port)))
    (if (not (eof-object? (peek-byte port)))

(md-file-chunks (open-input-string test-string) 1024)

for documentation.

This was tested on Windows, but ought to work elsewhere too.
You'll need a relatively new version of PLT Scheme, for
example 369.100.

It wasn't obvious whether you put the md-file-chunks in a module or
whether you are using the top-level. If you are using the top-level,
the line

    (require mzscheme)

makes sure primitive operations are inlined.

I'd love to hear your new timings.

PS: Remember to close file ports after use.

Jens Axel Søgaard

Posted on the users mailing list.