| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Data.HashMap.Monoidal
Contents
Description
This module provides a HashMap variant which uses the value's
Monoid instance to accumulate conflicting entries when merging
Maps.
While some functions mirroring those of HashMap are provided
here for convenience, more specialized needs will likely want to use
either the Newtype or Wrapped instances to manipulate the
underlying Map.
- newtype MonoidalHashMap k a = MonoidalHashMap {
- getMonoidalHashMap :: HashMap k a
- toList :: MonoidalHashMap k a -> [(k, a)]
- fromList :: (Eq k, Hashable k, Monoid a) => [(k, a)] -> MonoidalHashMap k a
- singleton :: (Eq k, Hashable k) => k -> a -> MonoidalHashMap k a
- size :: MonoidalHashMap k a -> Int
- member :: (Eq k, Hashable k) => k -> MonoidalHashMap k a -> Bool
- notMember :: (Eq k, Hashable k) => k -> MonoidalHashMap k a -> Bool
- lookup :: (Eq k, Hashable k) => k -> MonoidalHashMap k v -> Maybe v
- lookupM :: (Eq k, Hashable k, Monoid v) => k -> MonoidalHashMap k v -> v
- elems :: MonoidalHashMap k a -> [a]
- keys :: MonoidalHashMap k a -> [k]
- delete :: (Eq k, Hashable k) => k -> MonoidalHashMap k a -> MonoidalHashMap k a
- mapKeys :: (Monoid a, Hashable k, Eq k, Hashable k', Eq k') => (k -> k') -> MonoidalHashMap k a -> MonoidalHashMap k' a
- modify :: (Monoid a, Hashable k, Eq k) => (a -> a) -> k -> MonoidalHashMap k a -> MonoidalHashMap k a
- modifyDef :: (Monoid a, Hashable k, Eq k) => a -> (a -> a) -> k -> MonoidalHashMap k a -> MonoidalHashMap k a
- map :: (v1 -> v2) -> MonoidalHashMap k v1 -> MonoidalHashMap k v2
- filterWithKey :: (k -> v -> Bool) -> MonoidalHashMap k v -> MonoidalHashMap k v
Documentation
newtype MonoidalHashMap k a #
A HashMap with monoidal accumulation
Constructors
| MonoidalHashMap | |
Fields
| |
Instances
Often-needed functions
toList :: MonoidalHashMap k a -> [(k, a)] #
O(n*log n). Return a list of this map's elements. The list is produced lazily. The order of its elements is unspecified.
fromList :: (Eq k, Hashable k, Monoid a) => [(k, a)] -> MonoidalHashMap k a #
O(n*log n). Construct a map with the supplied mappings. If the list contains duplicate mappings, values will be merged using (mappend newVal oldVal).
singleton :: (Eq k, Hashable k) => k -> a -> MonoidalHashMap k a #
O(1). A map with a single element.
size :: MonoidalHashMap k a -> Int #
O(1). The number of elements in the map.
member :: (Eq k, Hashable k) => k -> MonoidalHashMap k a -> Bool #
O(log n). Is the key a member of the map? See also notMember.
notMember :: (Eq k, Hashable k) => k -> MonoidalHashMap k a -> Bool #
O(log n). Is the key not a member of the map? See also member.
lookup :: (Eq k, Hashable k) => k -> MonoidalHashMap k v -> Maybe v #
O(log n) Return the value to which the specified key is mapped,
or Nothing if this map contains no mapping for the key.
lookupM :: (Eq k, Hashable k, Monoid v) => k -> MonoidalHashMap k v -> v #
O(log n) Return the value to which the specified key is mapped, or mempty if this map contains no mapping for the key.
elems :: MonoidalHashMap k a -> [a] #
O(n). Return a list of this map's values. The list is produced lazily.
keys :: MonoidalHashMap k a -> [k] #
O(n). Return all keys of the map in ascending order. Subject to list fusion.
delete :: (Eq k, Hashable k) => k -> MonoidalHashMap k a -> MonoidalHashMap k a #
O(log n). Delete a key and its value from the map. When the key is not a member of the map, the original map is returned.
mapKeys :: (Monoid a, Hashable k, Eq k, Hashable k', Eq k') => (k -> k') -> MonoidalHashMap k a -> MonoidalHashMap k' a #
O(n). Map a function to each key of a map, if it will result in duplicated mappings, their values will be merged in unspecified order
modify :: (Monoid a, Hashable k, Eq k) => (a -> a) -> k -> MonoidalHashMap k a -> MonoidalHashMap k a #
O(log n). Modify a value on some key with a function, if value under key doesn't exist -- use mempty.
modifyDef :: (Monoid a, Hashable k, Eq k) => a -> (a -> a) -> k -> MonoidalHashMap k a -> MonoidalHashMap k a #
O(log n). Modify a value on some key with a function, providing a default value if that key doesn't exist.
map :: (v1 -> v2) -> MonoidalHashMap k v1 -> MonoidalHashMap k v2 #
O(n) Transform this map by applying a function to every value.
filterWithKey :: (k -> v -> Bool) -> MonoidalHashMap k v -> MonoidalHashMap k v #
O(n) Filter this map by retaining only elements satisfying a predicate.