Re: [Haskell-cafe] hash of a lazy bytestring?
On Sun, May 13, 2007 at 08:30:41AM -0700, David Roundy wrote: do l - readFile foo let len = length l writeFile bar l putStrLn $ Length is ++ show l Oops, of course this should have been show len in the last line. -- David Roundy http://www.darcs.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] hash of a lazy bytestring?
On Sun, 13 May 2007, David Roundy wrote: I was just contemplating hashes, and it occurred to me that it would be nice to be able to compute the hash of a lazily constructed bytestring and lazily consume its output without requiring the whole string to ever be in memory. Or in general, it'd be nice to be able to perform two simultaneous consumptions of a lazy list without requiring that the entire list be stored. How about reading the same file twice? do l1 - readFile foo l2 - readFile foo let len = length l1 writeFile bar l2 ... Another solution would be loop fusion: do l - readFile foo len - writeFileAndComputeLength bar l ... A compiler might be able to do that for you. Tom -- Tom Schrijvers Department of Computer Science K.U. Leuven Celestijnenlaan 200A B-3001 Heverlee Belgium tel: +32 16 327544 e-mail: [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] hash of a lazy bytestring?
On Sun, 13 May 2007, David Roundy wrote: I was just contemplating hashes, and it occurred to me that it would be nice to be able to compute the hash of a lazily constructed bytestring and lazily consume its output without requiring the whole string to ever be in memory. Or in general, it'd be nice to be able to perform two simultaneous consumptions of a lazy list without requiring that the entire list be stored. Another example would be computing the length of an ordinary list: do l - readFile foo let len = length l writeFile bar l putStrLn $ Length is ++ show l An elegant implementation of 'wc' is another example. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
