[Haskell-cafe] ANN: signed-multiset-0.1

Stefan Holdermans stefan at vectorfabrics.com
Fri Apr 20 11:02:09 CEST 2012


>> For a specific example, I haven't the faintest intuition about
>> what 'map' should do.  Suppose we have
>> 	{(k1)x1, (k2)x2}
>> and f x1 == f x2 = y.  Should the value of map f {...} be
>> {(k1+k2)y} or {(k1`max`k2)y} or what?
> Good question. I'd suppose that they should be parametrized by any (Abelian?) group on the weights/multiplicities, where (+) is the canonical one since we're talking about "negative" membership.

Any groupoid on the multiplicities would do, I guess.

As I wrote in my answer to Richard, max seems a better choise, as it nicely generalises mapping on sets.



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