On Fri, Jul 02, 2010 at 08:48:07PM -0400, Brandon S Allbery KF8NH wrote:
On 7/2/10 17:24 , Gregory Crosswhite wrote:
The problem with this approach is that the hash context isn't a monoid; you can absorb data into the context, but you can't combine two hash contexts to form a new one. Thus, the Writer monad won't work for this purpose.
No? The context is simply a String, which is a monoid, and you can combine contexts quite meaningfully before you actually compute the final hash (in fact, that's the whole point!).
The context isn't a string. it is an intermediate state in the algorithm of the hash function. it is usually an opaque binary blob (represented by a ByteString) of a size that is on the order of the final hash (unrelated to the size of the input). John -- John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/