module Data.Multimap.SetMultimap ( SetMultimap
                                 , delete, map
                                 , member', notMember'
                                 ) where

import Prelude hiding (map)
import qualified Data.Map as Map
import Data.Maybe (fromMaybe)
import Data.Multimap.Internal (Multimap(..), lift1)
import Data.Set (Set)
import qualified Data.Set as Set

-- | A multimap with 'Set' values.
type SetMultimap k v = Multimap k Set v

-- | Map over the multimap's values; useful since 'Set' is not a functor.
map :: (Ord k, Ord v1 , Ord v2) => (v1 -> v2) -> SetMultimap k v1 -> SetMultimap k v2
map f (Multimap m) = Multimap $ fmap (Set.map f) m

delete :: (Ord k, Ord v) => k -> v -> SetMultimap k v -> SetMultimap k v
delete k v = lift1 (Set.delete v) k

member' :: (Ord k, Ord v) => k -> v -> SetMultimap k v -> Bool
member' k v (Multimap m) = fromMaybe False . fmap (Set.member v) $ Map.lookup k m

notMember' :: (Ord k, Ord v) => k -> v -> SetMultimap k v -> Bool
notMember' k v mm = not $ member' k v mm