[Haskell-cafe] Re: Why no merge and listDiff?
will_n48 at yahoo.com
Wed Jan 20 14:34:15 EST 2010
Christian Maeder <Christian.Maeder <at> dfki.de> writes:
> Will Ness schrieb:
> > I meant strictly increasing ordered lists, without multiples, for which the
> > operations, 'merge' and 'minus', would also have to produce like lists, i.e
> > strictly increasing, without multiples.
> Why don't you use directly Data.Set?
It says it's based on size balanced Trees? I initially wondered why no such
fundamental operations as merge and minus for _lists_, in the stadard libraries?
Also, its to/from list conversions are O(n), so probably won't work for
I was told the trend is to move specifics to hackage packages, but I wonder why
shouldn't such fundamental operations be just included in standard Data.List?
> > I guess the first variety is more appropriate for bags, and the second one
> > - for sets. The two would have to be de-conflated for that. (?)
> There are also bags aka multisets:
it's too seems to be based on trees.
Data.Ordlist seems to be a good match, except for its conflation of
ascending/non-decreasing lists under one "ordered" category (i.e. sets/bags
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