Re: [Haskell-cafe] Implementing ParseChart with Data.Map

Hi Krasimir,

insert :: k -> v -> Chart k v -> Maybe (Chart k v)

where the result is (Just _) if the (k,v) is actually added to the chart or Nothing if it was already there and nothing have to be done.

insertLookupWithKey :: Ord k => (k -> a -> a -> a) -> k -> a -> Map k a -> (Maybe a, Map k a) This should provide the information you need, without the double traversal of the data structure. Thanks Neil