Hi,
Thanks for the benchmark. In light of this and your other arguments I think we should add the functions. Lets settle on the names. I currently dislike that we have 'lookup' and 'findDefault' (which is lookup with a default value.) We should agree on a principle for when we use the two words.
We should definitely settle on the names. At some point I thought maybe we could add just these two functions: predecessor :: Ord a => a -> Set a -> Maybe a successor :: Ord a => a -> Set a -> Maybe a These functions work like findLess, findGreater, i.e., they return a strict predecessor or successor of a given key. The key does not need to exist in the set/map. Are there any good use cases for findLessEqual/findGreaterEqual, instead of calling lookup and if it fails, call predecessor/successor? Cheers, Milan