1 -----------------------------------------------------------------------------
4 -- Copyright : (c) The University of Glasgow 2001
5 -- License : BSD-style (see the file libraries/core/LICENSE)
7 -- Maintainer : libraries@haskell.org
8 -- Stability : provisional
9 -- Portability : portable
11 -- $Id: Set.hs,v 1.1 2001/09/13 11:50:35 simonmar Exp $
13 -- This implementation of sets sits squarely upon Data.FiniteMap.
15 -----------------------------------------------------------------------------
18 Set, -- abstract, instance of: Eq
21 mkSet, -- :: Ord a => [a] -> Set a
22 setToList, -- :: Set a -> [a]
23 unitSet, -- :: a -> Set a
24 singletonSet, -- :: a -> Set a
26 union, -- :: Ord a => Set a -> Set a -> Set a
27 unionManySets, -- :: Ord a => [Set a] -> Set a
28 minusSet, -- :: Ord a => Set a -> Set a -> Set a
29 mapSet, -- :: Ord a => (b -> a) -> Set b -> Set a
30 intersect, -- :: Ord a => Set a -> Set a -> Set a
31 addToSet, -- :: Ord a => Set a -> a -> Set a
32 delFromSet, -- :: Ord a => Set a -> a -> Set a
34 elementOf, -- :: Ord a => a -> Set a -> Bool
35 isEmptySet, -- :: Set a -> Bool
37 cardinality -- :: Set a -> Int
45 -- This can't be a type synonym if you want to use constructor classes.
46 newtype Set a = MkSet (FiniteMap a ())
49 emptySet = MkSet emptyFM
52 unitSet x = MkSet (unitFM x ())
54 {-# DEPRECATED singletonSet "use Set.unitSet" #-}
55 singletonSet = unitSet -- old;deprecated.
57 setToList :: Set a -> [a]
58 setToList (MkSet set) = keysFM set
60 mkSet :: Ord a => [a] -> Set a
61 mkSet xs = MkSet (listToFM [ (x, ()) | x <- xs])
63 union :: Ord a => Set a -> Set a -> Set a
64 union (MkSet set1) (MkSet set2) = MkSet (plusFM set1 set2)
66 unionManySets :: Ord a => [Set a] -> Set a
67 unionManySets ss = foldr union emptySet ss
69 minusSet :: Ord a => Set a -> Set a -> Set a
70 minusSet (MkSet set1) (MkSet set2) = MkSet (minusFM set1 set2)
72 intersect :: Ord a => Set a -> Set a -> Set a
73 intersect (MkSet set1) (MkSet set2) = MkSet (intersectFM set1 set2)
75 addToSet :: Ord a => Set a -> a -> Set a
76 addToSet (MkSet set) a = MkSet (addToFM set a ())
78 delFromSet :: Ord a => Set a -> a -> Set a
79 delFromSet (MkSet set) a = MkSet (delFromFM set a)
81 elementOf :: Ord a => a -> Set a -> Bool
82 elementOf x (MkSet set) = isJust (lookupFM set x)
84 isEmptySet :: Set a -> Bool
85 isEmptySet (MkSet set) = sizeFM set == 0
87 mapSet :: Ord a => (b -> a) -> Set b -> Set a
88 mapSet f (MkSet set) = MkSet (listToFM [ (f key, ()) | key <- keysFM set ])
90 cardinality :: Set a -> Int
91 cardinality (MkSet set) = sizeFM set
94 instance (Eq a) => Eq (Set a) where
95 (MkSet set_1) == (MkSet set_2) = set_1 == set_2
96 (MkSet set_1) /= (MkSet set_2) = set_1 /= set_2
98 -- but not so clear what the right thing to do is:
100 instance (Ord a) => Ord (Set a) where
101 (MkSet set_1) <= (MkSet set_2) = set_1 <= set_2