Yes! intersectionWith is just what I needed. In any case, coming back to your example, why would you want to use undefined in that particular case? What makes it an interesting example ? Best, Jose On 28-05-2013 12:32, Johannes Waldmann wrote:
Jose A. Lopes
writes: unionWith :: Ord k => (a -> b -> c) -> Map k a -> Map k b -> Map k c
what should be the result of
unionWith undefined (M.singleton False 42) (M.singleton True "bar") ?
perhaps you mean intersectionWith, which already has the type you want.
- J.W.
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-- José António Branquinho de Oliveira Lopes Instituto Superior Técnico Technical University of Lisbon