Joining slightly late...
From: John Millikin <jmillikin@gmail.com>
John Lato's "iteratee" package is based on IterateeMCPS.hs[1]. I used
IterateeM.hs for "enumerator", because when I benchmarked them the non-CPS
version was something like 10% faster on most operations.
Based on tests I did before iteratee-0.4, the fastest implementation was Oleg's alternate design which is in the comments of IterateeM.hs. I don't think any current packages use that however, with good reason.
I'd be interested to see the results of a shootout between iteratee and enumerator. I would expect them to be basically equivalent most of the time, with maybe two or three operations with a small (but consistent) difference one way or the other.
John L.