[Haskell-cafe] Map unionWith generalization
Twan van Laarhoven
twanvl at gmail.com
Wed Jan 27 21:09:49 EST 2010
Hans Aberg wrote:
> For example, in Map String Integer (sparse representation of monomials)
> compute the minimum value of all associative pairs with the same key
> (the gcd); if only one key is present, the absent should be treated as
> having value 0. So
> unionWith min xs ys
> will not work, because unionWith will always apply the identity to the
> remaining value when one key is missing, whereas it should be sent to 0.
If missing keys represent 0, then wouldn't this work?
intersectionWith min xs ys
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