Serge D. Mechveliani wrote:
How do you think, maybe, Data.Set also needs to provide `lookup' ?
Admittingly, using 'Set.filter (==e) s' to find the matching element may be a bit slower. When trying to use 'Set.intersection s $ singleton e' I just noticed that intersection is not left-biased (see below)! I'm not sure if Data.Set should be extended to better support elements with an equivalence relation and a corresponding order. I've such sets too, but never really cared about the additional component. Do you also want functions 'insertWith', 'unionWith', 'splitLookup' (and what not)? I'ld rather suggest to use Data.Map instead and use a proper total order for the keys (although that may also be awkward). Christian *Main> findMin $ union (singleton $ D 0 "3") $ singleton $ D 0 "2" D 0 "3" *Main> findMin $ intersection (singleton $ D 0 "3") $ singleton $ D 0 "2" D 0 "2"