> {-# LANGUAGE TypeFamilies #-}

> module Data.SetClass
>      where


Import List
-----------

> import qualified Data.Set as S
> import qualified Data.IntSet as IS

> import Prelude hiding (null)


-------------------------------------

> class Set a where

>   type SetElem a

>   toList      :: a -> [SetElem a]
>   fromList    :: [SetElem a] -> a
>   size        :: a -> Int
>   intersection :: a -> a -> a
>   (\\)        :: a -> a -> a
>   union       :: a -> a -> a
>   null        :: a -> Bool
>   empty       :: a

>   disjunct    :: a -> a -> Bool
>   disjunct a b = null (intersection a b)

---------------------------

> instance Ord a => Set (S.Set a) where

>   type SetElem (S.Set a) = a

>   toList      = S.toList
>   fromList    = S.fromList
>   size        = S.size
>   intersection = S.intersection
>   (\\)        = (S.\\)
>   union       = S.union
>   null        = S.null
>   empty       = S.empty


> instance Set IS.IntSet where

>   type SetElem IS.IntSet = Int

>   toList      = IS.toList
>   fromList    = IS.fromList
>   size        = IS.size
>   intersection = IS.intersection
>   (\\)        = (IS.\\)
>   union       = IS.union
>   null        = IS.null
>   empty       = IS.empty