Safe Haskell  None 

Language  Haskell2010 
Map
type used to represent records and unions
Synopsis
 data Map k v
 empty :: Ord k => Map k v
 singleton :: k > v > Map k v
 fromList :: Ord k => [(k, v)] > Map k v
 fromListWithKey :: Ord k => (k > v > v > v) > [(k, v)] > Map k v
 unorderedSingleton :: k > v > Map k v
 unorderedFromList :: Ord k => [(k, v)] > Map k v
 sort :: Map k v > Map k v
 isSorted :: Eq k => Map k v > Bool
 insert :: Ord k => k > v > Map k v > Map k v
 insertWith :: Ord k => (v > v > v) > k > v > Map k v > Map k v
 delete :: Ord k => k > Map k v > Map k v
 filter :: Ord k => (a > Bool) > Map k a > Map k a
 restrictKeys :: Ord k => Map k a > Set k > Map k a
 withoutKeys :: Ord k => Map k a > Set k > Map k a
 mapMaybe :: Ord k => (a > Maybe b) > Map k a > Map k b
 lookup :: Ord k => k > Map k v > Maybe v
 member :: Ord k => k > Map k v > Bool
 uncons :: Ord k => Map k v > Maybe (k, v, Map k v)
 size :: Map k v > Int
 union :: Ord k => Map k v > Map k v > Map k v
 unionWith :: Ord k => (v > v > v) > Map k v > Map k v > Map k v
 outerJoin :: Ord k => (a > c) > (b > c) > (k > a > b > c) > Map k a > Map k b > Map k c
 intersection :: Ord k => Map k a > Map k b > Map k a
 intersectionWith :: Ord k => (a > b > c) > Map k a > Map k b > Map k c
 difference :: Ord k => Map k a > Map k b > Map k a
 mapWithKey :: (k > a > b) > Map k a > Map k b
 traverseWithKey :: Ord k => Applicative f => (k > a > f b) > Map k a > f (Map k b)
 unorderedTraverseWithKey :: Ord k => Applicative f => (k > a > f b) > Map k a > f (Map k b)
 unorderedTraverseWithKey_ :: Ord k => Applicative f => (k > a > f ()) > Map k a > f ()
 foldMapWithKey :: (Monoid m, Ord k) => (k > a > m) > Map k a > m
 toList :: Ord k => Map k v > [(k, v)]
 toAscList :: Map k v > [(k, v)]
 toMap :: Map k v > Map k v
 keys :: Map k v > [k]
 keysSet :: Map k v > Set k
 elems :: Ord k => Map k v > [v]
Type
A Map
that remembers the original ordering of keys
This is primarily used so that formatting preserves field order
This is done primarily to avoid a dependency on insertorderedcontainers
and also to improve performance
Instances
Functor (Map k) Source #  
Ord k => Foldable (Map k) Source #  
Defined in Dhall.Map fold :: Monoid m => Map k m > m # foldMap :: Monoid m => (a > m) > Map k a > m # foldr :: (a > b > b) > b > Map k a > b # foldr' :: (a > b > b) > b > Map k a > b # foldl :: (b > a > b) > b > Map k a > b # foldl' :: (b > a > b) > b > Map k a > b # foldr1 :: (a > a > a) > Map k a > a # foldl1 :: (a > a > a) > Map k a > a # elem :: Eq a => a > Map k a > Bool # maximum :: Ord a => Map k a > a # minimum :: Ord a => Map k a > a #  
Ord k => Traversable (Map k) Source #  
Ord k => IsList (Map k v) Source #  
(Ord k, Eq v) => Eq (Map k v) Source #  
(Data k, Data v, Ord k) => Data (Map k v) Source #  
Defined in Dhall.Map gfoldl :: (forall d b. Data d => c (d > b) > d > c b) > (forall g. g > c g) > Map k v > c (Map k v) # gunfold :: (forall b r. Data b => c (b > r) > c r) > (forall r. r > c r) > Constr > c (Map k v) # toConstr :: Map k v > Constr # dataTypeOf :: Map k v > DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) > Maybe (c (Map k v)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) > Maybe (c (Map k v)) # gmapT :: (forall b. Data b => b > b) > Map k v > Map k v # gmapQl :: (r > r' > r) > r > (forall d. Data d => d > r') > Map k v > r # gmapQr :: (r' > r > r) > r > (forall d. Data d => d > r') > Map k v > r # gmapQ :: (forall d. Data d => d > u) > Map k v > [u] # gmapQi :: Int > (forall d. Data d => d > u) > Map k v > u # gmapM :: Monad m => (forall d. Data d => d > m d) > Map k v > m (Map k v) # gmapMp :: MonadPlus m => (forall d. Data d => d > m d) > Map k v > m (Map k v) # gmapMo :: MonadPlus m => (forall d. Data d => d > m d) > Map k v > m (Map k v) #  
(Ord k, Ord v) => Ord (Map k v) Source # 

(Show k, Show v, Ord k) => Show (Map k v) Source #  
Generic (Map k v) Source #  
Ord k => Semigroup (Map k v) Source #  \x y z > x <> (y <> z) == (x <> y) <> (z :: Map Int Int) 
Ord k => Monoid (Map k v) Source #  \x > x <> mempty == (x :: Map Int Int) \x > mempty <> x == (x :: Map Int Int) 
(Data k, Data v, Lift k, Lift v, Ord k) => Lift (Map k v) Source #  
(NFData k, NFData v) => NFData (Map k v) Source #  
type Rep (Map k v) Source #  
type Item (Map k v) Source #  
Construction
singleton :: k > v > Map k v Source #
Create a Map
from a single keyvalue pair
>>>
singleton "A" 1
fromList [("A",1)]
fromList :: Ord k => [(k, v)] > Map k v Source #
Create a Map
from a list of keyvalue pairs
>>>
fromList [("B",1),("A",2)]  The map preserves order
fromList [("B",1),("A",2)]>>>
fromList [("A",1),("A",2)]  For duplicates, later values take precedence
fromList [("A",2)]
Note that this handling of duplicates means that fromList
is not a monoid
homomorphism:
>>>
fromList [(1, True)] <> fromList [(1, False)]
fromList [(1,True)]>>>
fromList ([(1, True)] <> [(1, False)])
fromList [(1,False)]
fromListWithKey :: Ord k => (k > v > v > v) > [(k, v)] > Map k v Source #
Create a Map
from a list of keyvalue pairs with a combining function.
>>>
fromListWithKey (\k v1 v2 > k ++ v1 ++ v2) [("B","v1"),("A","v2"),("B","v3")]
fromList [("B","Bv3v1"),("A","v2")]
Constructing unordered
Map
s
unorderedSingleton :: k > v > Map k v Source #
Create a Map
from a single keyvalue pair.
Any further operations on this map will not retain the order of the keys.
>>>
unorderedSingleton "A" 1
fromList [("A",1)]
unorderedFromList :: Ord k => [(k, v)] > Map k v Source #
Create a Map
from a list of keyvalue pairs
Any further operations on this map will not retain the order of the keys.
>>>
unorderedFromList []
fromList []>>>
unorderedFromList [("B",1),("A",2)]  The map /doesn't/ preserve order
fromList [("A",2),("B",1)]>>>
unorderedFromList [("A",1),("A",2)]  For duplicates, later values take precedence
fromList [("A",2)]
Sorting
sort :: Map k v > Map k v Source #
Sort the keys of a Map
, forgetting the original ordering
sort (sort x) = sort x
>>>
sort (fromList [("B",1),("A",2)])
fromList [("A",2),("B",1)]
isSorted :: Eq k => Map k v > Bool Source #
Check if the keys of a Map
are already sorted
isSorted (sort m) = True
>>>
isSorted (fromList [("B",1),("A",2)])  Sortedness is based only on keys
False>>>
isSorted (fromList [("A",2),("B",1)])
True
Insertion
insert :: Ord k => k > v > Map k v > Map k v Source #
Insert a keyvalue pair into a Map
, overriding any previous value stored
underneath the same key, if present
insert = insertWith (\v _ > v)
>>>
insert "C" 1 (fromList [("B",2),("A",3)])  Values are inserted on left
fromList [("C",1),("B",2),("A",3)]>>>
insert "C" 1 (fromList [("C",2),("A",3)])  New value takes precedence
fromList [("C",1),("A",3)]
insertWith :: Ord k => (v > v > v) > k > v > Map k v > Map k v Source #
Insert a keyvalue pair into a Map
, using the supplied function to combine
the new value with any old value underneath the same key, if present
>>>
insertWith (+) "C" 1 (fromList [("B",2),("A",3)])  No collision
fromList [("C",1),("B",2),("A",3)]>>>
insertWith (+) "C" 1 (fromList [("C",2),("A",3)])  Collision
fromList [("C",3),("A",3)]
Deletion/Update
filter :: Ord k => (a > Bool) > Map k a > Map k a Source #
Keep all values that satisfy the given predicate
>>>
filter even (fromList [("C",3),("B",2),("A",1)])
fromList [("B",2)]>>>
filter odd (fromList [("C",3),("B",2),("A",1)])
fromList [("C",3),("A",1)]
Query
lookup :: Ord k => k > Map k v > Maybe v Source #
Retrieve a key from a Map
lookup k mempty = empty lookup k (x <> y) = lookup k y <> lookup k x
>>>
lookup "A" (fromList [("B",1),("A",2)])
Just 2>>>
lookup "C" (fromList [("B",1),("A",2)])
Nothing
member :: Ord k => k > Map k v > Bool Source #
Check if a key belongs to a Map
member k mempty = False member k (x <> y) = member k x  member k y
>>>
member "A" (fromList [("B",1),("A",2)])
True>>>
member "C" (fromList [("B",1),("A",2)])
False
Combine
unionWith :: Ord k => (v > v > v) > Map k v > Map k v > Map k v Source #
Combine two Map
s using a combining function for colliding keys
>>>
unionWith (+) (fromList [("D",1),("C",2)]) (fromList [("B",3),("A",4)])
fromList [("D",1),("C",2),("B",3),("A",4)]>>>
unionWith (+) (fromList [("D",1),("C",2)]) (fromList [("C",3),("A",4)])
fromList [("D",1),("C",5),("A",4)]
outerJoin :: Ord k => (a > c) > (b > c) > (k > a > b > c) > Map k a > Map k b > Map k c Source #
A generalised unionWith
.
>>>
outerJoin Left Left (\k a b > Right (k, a, b)) (fromList [("A",1),("B",2)]) (singleton "A" 3)
fromList [("A",Right ("A",1,3)),("B",Left 2)]
This function is much inspired by the Data.Semialign.Semialign class.
Traversals
mapWithKey :: (k > a > b) > Map k a > Map k b Source #
Transform the values of a Map
using their corresponding key
mapWithKey (pure id) = id mapWithKey (liftA2 (.) f g) = mapWithKey f . mapWithKey g
mapWithKey f mempty = mempty mapWithKey f (x <> y) = mapWithKey f x <> mapWithKey f y
>>>
mapWithKey (,) (fromList [("B",1),("A",2)])
fromList [("B",("B",1)),("A",("A",2))]
traverseWithKey :: Ord k => Applicative f => (k > a > f b) > Map k a > f (Map k b) Source #
Traverse all of the keyvalue pairs in a Map
, in their original order
>>>
traverseWithKey (,) (fromList [("B",1),("A",2)])
("BA",fromList [("B",1),("A",2)])
unorderedTraverseWithKey :: Ord k => Applicative f => (k > a > f b) > Map k a > f (Map k b) Source #
Same as traverseWithKey
, except that the order of effects is not
necessarily the same as the order of the keys
unorderedTraverseWithKey_ :: Ord k => Applicative f => (k > a > f ()) > Map k a > f () Source #
Traverse all of the keyvalue pairs in a Map
, not preserving their
original order, where the result of the computation can be forgotten.
Note that this is a strict traversal, fully traversing the map even when the Applicative is lazy in the remaining elements.
foldMapWithKey :: (Monoid m, Ord k) => (k > a > m) > Map k a > m Source #
Fold all of the keyvalue pairs in a Map
, in their original order
>>>
foldMapWithKey (,) (fromList [("B",[1]),("A",[2])])
("BA",[1,2])
Conversions
toList :: Ord k => Map k v > [(k, v)] Source #
Convert a Map
to a list of keyvalue pairs in the original order of keys
>>>
toList (fromList [("B",1),("A",2)])
[("B",1),("A",2)]
toAscList :: Map k v > [(k, v)] Source #
Convert a Map
to a list of keyvalue pairs in ascending order of keys
keys :: Map k v > [k] Source #
Return the keys from a Map
in their original order
>>>
keys (fromList [("B",1),("A",2)])
["B","A"]