Malte Milatz
See the following link for a purely functional and straight-forward implementation of SHA1. Disclaimer: Please be kind to me, I haven't done much Haskell (yet). And I know nothing about SHA1 except its specification.
It performs better than the SHA1 algorithm in Crypto: It is faster by a factor of approximately e. It is also competitive (regarding time) with the »unsafe« SHA1 implementation posted here some days ago,
Great. Can you post some timings?
although it uses considerably more memory. Of course, you may safely
Does it have a space leak or does it run in constant but larger space than the other versions?
forget it if you're interested in performance near a C implementation such as GNU sha1sum.
I don't think it's unreasonable to think we could get near to C performance and we've been getting closer.
I'd heartily welcome any comments or suggestions for improvement, as well as benchmark results, especially if they differ from mine. I'm using the standard ghc -O2, by the way.
For me it will have to wait until next weekend at the very earliest but I hope your post sparks some interest in the meantime. Dominic. PS I had a 5 minute (well actually less) look at the code and it doesn't look dissimilar to other versions I've seen in Haskell. I wonder if the speedup is principally because of ByteString. PPS We have to put splitn in a library.