[Haskell-cafe] Re: Create a list without duplicates from a list
haskell at list.mightyreason.com
Sat Feb 9 08:19:22 EST 2008
For Bimap is there anything like Data.Map.insertWithKey ?
Stuart Cook wrote:
> On Sat, Feb 9, 2008 at 7:36 AM, Dan Weston <westondan at imageworks.com> wrote:
>> If order is important, the new bijective Data.Bimap class
>> may be your best bet (I haven't yet tried it myself).
> Let me try:
> nub :: (Ord a) => [a] -> [a]
> nub = map snd . Data.Bimap.toAscList . Data.Bimap.fromList . reverse
> . zip [1..]
> > nub "hello, world!"
> "helo, wrd!"
> Without the call to (reverse), this would still be an order-preserving
> nub, except that it would preserve the relative order of the *last*
> occurrence of each element. Actually, this makes me wonder whether
> fromList's behaviour should be changed, and whether I should add a
> "non-clobbering" variant of insert.
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