On 2008.08.26 12:09:05 +0100, "Bayley, Alistair"
The name is... well, pessimal might be a bit strong, but few programmers would think to look for something called "nub". Personally, when I first looked for it I expected uniq or unique (because that's what the unix utility that does the same thing is called). Distinct (from SQL) is another name that occurred to me, but never nub... it's not even a synonym for unique: http://thesaurus.reference.com/browse/unique
See the redefinition of nub as uniq here (which I assume is because John didn't know about nub): http://hackage.haskell.org/packages/archive/MissingH/1.0.0/doc/html/Data -List-Utils.html
The folklore (such as it is) for uniq is that it is trivially defined like so (for lists):
uniq = map head . group . sort
and so perhaps is not worthy of library inclusion? BTW, is this a suitably performant definition, or would we benefit from a lower-level implementation?
Alistair
FWIW, when I tested out a number of nub/uniq definitions, the map head version performed the worst, much worse than the O(n^2) one everyone is complaining about. It's a neat definition, but not performant. -- gwern Iraq Hercules Bosnia Summercon Compsec 20 Albright EuroFed RDI encryption