[mercury-users] file compression in Mercury

[Ralph Becket]

> From: Robert Ernst Johann JESCHOFNIK 
> 
> On Wed, 16 Feb 2000, Erwan Jahier wrote:
> 
> > Hi.
> > 
> > Has anyone ever implemented a Mercury program that performs 
> file (image or text) 
> > compression?
> 
> 
> Didn't Ralph do something like this? I remember reading 
> something about compression..

I did indeed - I've got a fast, efficient implementation of LZW
compression as taken from the 129.compress SPEC95 benchmark.  It
runs at about half the speed of the C version.  I think the
decompression program has drifted slightly out sync with the
compressor so I'll take a look and submit it (well, as soon as
MSR's lawyers get back to me about licenses etc. - hopefully
there won't be a problem).

One of the problems implementing LZW in Mercury is that one has
to pass a lot of state around; I think it would make an excellent
candidate to demonstrate the simplifying power of EDCGs.  I've
been meaning to try EDCGs out for a while, but there hasn't been
a stable ROTD available since 0.9.1 came out.

Cheers,

Ralph
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