On Wed, Feb 24, 2010 at 3:23 PM, Gwern Branwen
nub . sort (and the reverse) are very frequent. The attached sort.txt was produced by
find bin/ -name "*.hs" -exec sh -c "grep sort {} | grep nub && echo {}" \; > sort.txt
It's very crude and obviously produces lots of false positives & negatives, but even so, there's at least >50 uses of nub . sort etc.
Incidentally, data-ordlist has a nubSort implementation that's never more expensive than Data.List.sort. It's the same mergesort algorithm provided in Data.List except that it removes duplicates as it merges the lists. The library also provides a linear-time nub and nubBy on ordered lists, however this implementation is not used as part of nubSort. http://hackage.haskell.org/package/data-ordlist Best, Leon