Dear GHC team, I am looking into the .html docs on the libraries of Map and Set. Here follow the questions and notices. 1. elems :: Set a -> [a] setToList :: Set a -> [a] These two look like synonyms, but have different comments. Am I missing something? 2. size :: Set a -> Int -- O(1) ... And for large sets, the user needs to program genericSize :: Set a -> Integer genericSize = genericLength . Data.Set.elems ? Is this possible to make it O(1) too? 3. Data.Map has lookup and findWithDefault. According to name correspondence, a natural name for the latter would be lookupWithDefault - ? 4. Data.Set.intersection. In old library, it was `intersect' -- if I recall correct. So, it is natural to include `intersect' to the `Obsolete' list. 5. Name resolution. ./Prelude0.hs:254:28: Ambiguous occurrence `null' It could refer to either `Data.Set.null', imported from Data.Set at ./Prelude0.hs:50:48-51 or `GHC.List.null', imported from Prelude at ./Prelude0 Could the compiler detect where null applies to list and where to Set ? For this is visible from the types in the user program. 6. My module applies Data.Set.null (s :: Set a), and null (xs :: [a]). Why ghc reports of the clash with GHC.List.null ? Is GHC.List same as old List library module? Should I write import GHC.List (genericLength, null) instead of import List (genericLength) ? With kind regards, ----------------- Serge Mechveliani mechvel@botik.ru