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 -- This implementation of sets sits squarely upon Data.FiniteMap.
13 -----------------------------------------------------------------------------
16 Set, -- abstract, instance of: Eq
19 mkSet, -- :: Ord a => [a] -> Set a
20 setToList, -- :: Set a -> [a]
21 unitSet, -- :: a -> Set a
22 singletonSet, -- :: a -> Set a
24 union, -- :: Ord a => Set a -> Set a -> Set a
25 unionManySets, -- :: Ord a => [Set a] -> Set a
26 minusSet, -- :: Ord a => Set a -> Set a -> Set a
27 mapSet, -- :: Ord a => (b -> a) -> Set b -> Set a
28 intersect, -- :: Ord a => Set a -> Set a -> Set a
29 addToSet, -- :: Ord a => Set a -> a -> Set a
30 delFromSet, -- :: Ord a => Set a -> a -> Set a
32 elementOf, -- :: Ord a => a -> Set a -> Bool
33 isEmptySet, -- :: Set a -> Bool
35 cardinality -- :: Set a -> Int
43 -- This can't be a type synonym if you want to use constructor classes.
44 newtype Set a = MkSet (FiniteMap a ())
47 emptySet = MkSet emptyFM
50 unitSet x = MkSet (unitFM x ())
52 {-# DEPRECATED singletonSet "use Set.unitSet" #-}
53 singletonSet = unitSet -- old;deprecated.
55 setToList :: Set a -> [a]
56 setToList (MkSet set) = keysFM set
58 mkSet :: Ord a => [a] -> Set a
59 mkSet xs = MkSet (listToFM [ (x, ()) | x <- xs])
61 union :: Ord a => Set a -> Set a -> Set a
62 union (MkSet set1) (MkSet set2) = MkSet (plusFM set1 set2)
64 unionManySets :: Ord a => [Set a] -> Set a
65 unionManySets ss = foldr union emptySet ss
67 minusSet :: Ord a => Set a -> Set a -> Set a
68 minusSet (MkSet set1) (MkSet set2) = MkSet (minusFM set1 set2)
70 intersect :: Ord a => Set a -> Set a -> Set a
71 intersect (MkSet set1) (MkSet set2) = MkSet (intersectFM set1 set2)
73 addToSet :: Ord a => Set a -> a -> Set a
74 addToSet (MkSet set) a = MkSet (addToFM set a ())
76 delFromSet :: Ord a => Set a -> a -> Set a
77 delFromSet (MkSet set) a = MkSet (delFromFM set a)
79 elementOf :: Ord a => a -> Set a -> Bool
80 elementOf x (MkSet set) = isJust (lookupFM set x)
82 isEmptySet :: Set a -> Bool
83 isEmptySet (MkSet set) = sizeFM set == 0
85 mapSet :: Ord a => (b -> a) -> Set b -> Set a
86 mapSet f (MkSet set) = MkSet (listToFM [ (f key, ()) | key <- keysFM set ])
88 cardinality :: Set a -> Int
89 cardinality (MkSet set) = sizeFM set
92 instance (Eq a) => Eq (Set a) where
93 (MkSet set_1) == (MkSet set_2) = set_1 == set_2
94 (MkSet set_1) /= (MkSet set_2) = set_1 /= set_2
96 -- but not so clear what the right thing to do is:
98 instance (Ord a) => Ord (Set a) where
99 (MkSet set_1) <= (MkSet set_2) = set_1 <= set_2