On 2/8/09, Evan Laforge
I have a little util library with various map functions. 'within' is almost what you want, except it's half-open. You can make an inclusive one by pulling the lowest element off the above map.
I'm also curious if there's a better way to do this...
-- | Like Map.split, except include a matched key in the above map. split_map :: (Ord k) => k -> Map.Map k a -> (Map.Map k a, Map.Map k a) split_map k fm = (pre, post') where (pre, at, post) = Map.splitLookup k fm post' = maybe post (\v -> Map.insert k v post) at
-- | Split the map into the maps below, within, and above the given range. -- @low@ to @high@ is half-open, as usual. split3_map :: (Ord k) => k -> k -> Map.Map k a -> (Map.Map k a, Map.Map k a, Map.Map k a) split3_map low high fm = (below, within, way_above) where (below, above) = split_map low fm (within, way_above) = split_map high above
within low high fm = let (_, m, _) = split3_map low high fm in m
This looks right to me (correct time complexity). It should do what I need. I will test it and see what I discover. Thanks, Jared.