Data.Bimap

Contents

Description

An implementation of bidirectional maps between values of two key types. A Bimap is essentially a bijection between subsets of its two argument types.

Each element of the left-hand type is associated with an element of the right-hand type, and vice-versa, such that the two mappings are inverses. Deleting an element will cause its twin to be deleted, and inserting a pair of elements will cause any overlapping bindings to be deleted.

Most functions implicitly consider the left-hand type to be the key, and the right-hand type to be the value. Functions with an R suffix reverse this convention, treating the right-hand type as the key and the left-hand type as the value.

Synopsis

Bimap type

data Bimap a b

A bidirectional map between values of types a and b.

Instances

(Eq a, Eq b) => Eq (Bimap a b)
(Show a, Show b) => Show (Bimap a b)

Query

null :: Bimap a b -> Bool

O(1). Is the bimap empty? Version: 0.2

size :: Bimap a b -> Int

O(1). The number of elements in the bimap. Version: 0.2

member :: (Ord a, Ord b) => a -> Bimap a b -> Bool

O(log n). Is the specified value a member of the bimap? Version: 0.2

memberR :: (Ord a, Ord b) => b -> Bimap a b -> Bool

O(log n). A version of member specialized to the right key. Version: 0.2

notMember :: (Ord a, Ord b) => a -> Bimap a b -> Bool

O(log n). Is the specified value not a member of the bimap? Version: 0.2

notMemberR :: (Ord a, Ord b) => b -> Bimap a b -> Bool

O(log n). A version of notMember specialized to the right key. Version: 0.2

pairMember :: (Ord a, Ord b) => (a, b) -> Bimap a b -> Bool

O(log n). Are the two values associated with each other in the bimap?

This function is uncurried in its first two arguments, so that it can be used infix.

Version: 0.2

pairNotMember :: (Ord a, Ord b) => (a, b) -> Bimap a b -> Bool

O(log n). Are the two values not in the bimap, or not associated with each other? (Complement of pairMember.) Version: 0.2

lookup :: (Ord a, Ord b, Monad m) => a -> Bimap a b -> m b

O(log n). Lookup a left key in the bimap, returning the associated right key.

This function will return the result in the monad, or fail if the value isn't in the bimap.

Version: 0.2

lookupR :: (Ord a, Ord b, Monad m) => b -> Bimap a b -> m a

O(log n). A version of lookup that is specialized to the right key, and returns the corresponding left key. Version: 0.2

(!) :: (Ord a, Ord b) => Bimap a b -> a -> b

O(log n). Find the right key corresponding to a given left key. Calls error when the key is not in the bimap. Version: 0.2

(!>) :: (Ord a, Ord b) => Bimap a b -> b -> a

O(log n). A version of (!) that is specialized to the right key, and returns the corresponding left key. Version: 0.2

Construction

empty :: Bimap a b

O(1). The empty bimap. Version: 0.2

singleton :: a -> b -> Bimap a b

O(1). A bimap with a single element. Version: 0.2

Update

insert :: (Ord a, Ord b) => a -> b -> Bimap a b -> Bimap a b

O(log n). Insert a pair of values into the bimap, associating them.

If either of the values is already in the bimap, any overlapping bindings are deleted.

Version: 0.2

tryInsert :: (Ord a, Ord b) => a -> b -> Bimap a b -> Bimap a b

O(log n). Insert a pair of values into the bimap, but only if neither is already in the bimap. Version: 0.2.2

delete :: (Ord a, Ord b) => a -> Bimap a b -> Bimap a b

O(log n). Delete a value and its twin from a bimap.

When the value is not a member of the bimap, the original bimap is returned.

Version: 0.2

deleteR :: (Ord a, Ord b) => b -> Bimap a b -> Bimap a b

O(log n) A version of delete specialized to the right key. Version: 0.2

Min/Max

findMin :: Bimap a b -> (a, b)

O(log n). Find the element with minimal left key. Calls error if the bimap is empty. Version: 0.2.2

findMinR :: Bimap a b -> (b, a)

O(log n). Find the element with minimal right key. The right-hand key is the first entry in the pair. Calls error if the bimap is empty. Version: 0.2.2

findMax :: Bimap a b -> (a, b)

O(log n). Find the element with maximal left key. Calls error if the bimap is empty. Version: 0.2.2

findMaxR :: Bimap a b -> (b, a)

O(log n). Find the element with maximal right key. The right-hand key is the first entry in the pair. Calls error if the bimap is empty. Version: 0.2.2

deleteMin :: Ord b => Bimap a b -> Bimap a b

O(log n). Delete the element with minimal left key. Calls error if the bimap is empty. Version: 0.2.2

deleteMinR :: Ord a => Bimap a b -> Bimap a b

O(log n). Delete the element with minimal right key. Calls error if the bimap is empty. Version: 0.2.2

deleteMax :: Ord b => Bimap a b -> Bimap a b

O(log n). Delete the element with maximal left key. Calls error if the bimap is empty. Version: 0.2.2

deleteMaxR :: Ord a => Bimap a b -> Bimap a b

O(log n). Delete the element with maximal right key. Calls error if the bimap is empty. Version: 0.2.2

deleteFindMin :: Ord b => Bimap a b -> ((a, b), Bimap a b)

O(log n). Delete and find the element with minimal left key. Calls error if the bimap is empty. Version: 0.2.2

deleteFindMinR :: Ord a => Bimap a b -> ((b, a), Bimap a b)

O(log n). Delete and find the element with minimal right key. Calls error if the bimap is empty. Version: 0.2.2

deleteFindMax :: Ord b => Bimap a b -> ((a, b), Bimap a b)

O(log n). Delete and find the element with maximal left key. Calls error if the bimap is empty. Version: 0.2.2

deleteFindMaxR :: Ord a => Bimap a b -> ((b, a), Bimap a b)

O(log n). Delete and find the element with maximal right key. Calls error if the bimap is empty. Version: 0.2.2

Filter

filter :: (Ord a, Ord b) => (a -> b -> Bool) -> Bimap a b -> Bimap a b

O(n). Filter all association pairs that satisfy the predicate.

Note that the predicate will be applied twice for each association in the bimap.

Version: 0.2.4

partition :: (Ord a, Ord b) => (a -> b -> Bool) -> Bimap a b -> (Bimap a b, Bimap a b)

O(n). Partition the bimap according to a predicate. The first bimap contains all associations that satisfy the predicate; the second contains all associations that fail the predicate.

Note that the predicate will be applied twice for each association in the bimap.

Version: 0.2.4

Conversion/traversal

fromList :: (Ord a, Ord b) => [(a, b)] -> Bimap a b

O(n*log n). Build a map from a list of pairs. If there are any overlapping pairs in the list, the later ones will override the earlier ones. Version: 0.2

fromAList :: (Ord a, Ord b) => [(a, b)] -> Bimap a b

O(n*log n). Build a map from a list of pairs. Unlike fromList, earlier pairs will take precedence over later ones.

The name fromAList is a reference to Lisp-style association lists, where associations can be overridden by prepending new ones.

Note that when duplicates occur in both the keys and in the values, fromList xs /= fromAList (reverse xs). However, if either contains no duplicates, then the equality holds.

Version: 0.2.2

fromAscPairList :: (Ord a, Ord b) => [(a, b)] -> Bimap a b

O(n). Build a bimap from a list of pairs, where both the fst and snd halves of the list are in strictly ascending order.

This precondition is checked; an invalid list will cause an error.

Version: 0.2.3

fromAscPairListUnchecked :: (Ord a, Ord b) => [(a, b)] -> Bimap a b

O(n). Build a bimap from a list of pairs, where both the fst and snd halves of the list are in strictly ascending order.

This precondition is not checked; an invalid list will produce a malformed bimap.

Version: 0.2.3

toList :: Bimap a b -> [(a, b)]

O(n). Convert to a list of associated pairs. Version: 0.2

toAscList :: Bimap a b -> [(a, b)]

O(n). Convert to a list of associated pairs, with the left-hand values in ascending order.

Since pair ordering is lexical, the pairs will also be in ascending order.

Version: 0.2

toAscListR :: Bimap a b -> [(b, a)]

O(n). Convert to a list of associated pairs, with the right-hand values first in the pair and in ascending order.

Since pair ordering is lexical, the pairs will also be in ascending order.

Version: 0.2

keys :: Bimap a b -> [a]

O(n). Return all left-hand keys in the bimap in ascending order. Version: 0.2

keysR :: Bimap a b -> [b]

O(n). Return all right-hand keys in the bimap in ascending order. Version: 0.2

elems :: Bimap a b -> [b]

O(n). An alias for keysR. Version: 0.2

assocs :: Bimap a b -> [(a, b)]

O(n). Return all associated pairs in the bimap, with the left-hand values in ascending order. Version: 0.2

fold :: (a -> b -> c -> c) -> c -> Bimap a b -> c

O(n). Fold the association pairs in the map, such that fold f z == foldr f z . assocs. Version: 0.2

toMap :: Bimap a b -> Map a b

O(1). Extract only the left-to-right component of a bimap. Version: 0.2.1

toMapR :: Bimap a b -> Map b a

O(1). Extract only the right-to-left component of a bimap. Version: 0.2.1

Miscellaneous

valid :: (Ord a, Ord b) => Bimap a b -> Bool

O(n*log n). Test if the internal bimap structure is valid. This should be true for any bimap created using the public interface, unless fromAscPairListUnchecked has been used inappropriately. Version: 0.2

twist :: Bimap a b -> Bimap b a

O(1). Reverse the positions of the two element types in the bimap. Version: 0.2

twisted :: (Bimap a b -> Bimap a b) -> Bimap b a -> Bimap b a

O(1). Reverse the positions of the two element types in a bimap transformation. Version: 0.2