On Mon, Jul 09, 2007 at 09:15:07PM +0100, Andrew Coppin wrote:
Bulat Ziganshin wrote:
Hello Andrew,
Sunday, July 8, 2007, 7:07:59 PM, you wrote:
i don't think that ppm is so complex - it's just probability of symbol in some context. it's just too slow in naive implementation
Oh, sure, the *idea* is simple enough. Trying to actually *implement* it correctly is something else... ;-)
Took me about an hour and 50 lines of code (about a year ago - this was one of my first Haskell programs) to implement a PPM (de)compressor that didn't crash, always generated the same output as input, and achieved 50% ratios on its own source code (not quite as good as gzip, but what do you expect from a completely untuned compressor?). Peak throughput: 2 bits / sec. :)
the jhc is very different story
Yes - last I heard, it's an experimental research project rather than a production-ready compiler...
Correct. It requires 5 minutes and 600MB of RAM to compile Hello, World, and fails with internal pattern match errors on anything significantly larger. Stefan