On Thu, Nov 28, 2002 at 10:21:53PM +0000, Alistair Bayley wrote:
Wouldn't this have been better called "unique"? (analogous to the Unix program "uniq"). I was looking for a "unique" in the GHC Data.List library a few days ago, and didn't see one, so I wrote my own (not realising that was what "nub" did).
No, Unix uniq makes only a single pass. uniq = map head . group (A much tidier definition than the one I gave a few days ago :-) By contrast, "nub" removes duplicate elements from the list no matter where they are. I think both functions are useful. If I understand it right, uniq can evaluate its argument list lazily, while nub cannot. There's no real need to put uniq in the standard library, though. Hmm, but with that said, I don't think I disagree with you. Renaming "nub" to "unique" makes it clear that it is similar, but not identical to what Unix "uniq" does. Richard Braakman