The old FiniteMap module contains the addListToFM* functions that are missing in Data.Map. But how to implement it? First answer: insertList_foldl :: Ord k => [(k,a)] -> Map.Map k a -> Map.Map k a insertList_foldl = flip (foldl ins) where fluc = flip . uncurry ins = fluc Map.insert Second answer: insertList_union :: Ord k => [(k,a)] -> Map.Map k a -> Map.Map k a insertList_union kas = Map.union (Map.fromList kas) Situation and Problem: We already have a map of size n and want to insert a list with m elements. Then we look at the documentation and one gets: * For the first answer we do need O(sum_{i=0}^{m-1}log(n+i)) = O(log((m+n)!/n!)) operations. * For the sencond answer we do need O(m*log(m))+O(n+m) = O(m*log(m)+n+m) operations. These terms are hard to compare but a plot shows that insertList_foldl should be faster than insertList_union. But a testprogram shows that insertList_union is faster (and needs less memory) whatever the sizes of n and m are. So my questions are: Why are the insertList* functions missing? How would the library implementors implement insertList* and why? thanks, -- -- Mirko Rahn -- Tel +49-721 608 7504 -- --- http://liinwww.ira.uka.de/~rahn/ ---