Data.Map

keys :: forall v k. Map k v -> Set k

data Map k v

Map k v represents maps from keys of type k to values of type v.

Instances

• (Eq k) => Eq1 (Map k)
• (Eq k, Eq v) => Eq (Map k v)
• (Ord k) => Ord1 (Map k)
• (Ord k, Ord v) => Ord (Map k v)
• (Show k, Show v) => Show (Map k v)
• (Ord k) => Semigroup (Map k v)
• (Ord k) => Monoid (Map k v)
• Functor (Map k)
• FunctorWithIndex k (Map k)
• Foldable (Map k)
• FoldableWithIndex k (Map k)
• Traversable (Map k)
• TraversableWithIndex k (Map k)

values :: forall v k. Map k v -> List v

Get a list of the values contained in a map

update :: forall v k. Ord k => (v -> Maybe v) -> k -> Map k v -> Map k v

Update or delete the value for a key in a map

unions :: forall f v k. Ord k => Foldable f => f (Map k v) -> Map k v

Compute the union of a collection of maps

unionWith :: forall v k. Ord k => (v -> v -> v) -> Map k v -> Map k v -> Map k v

Compute the union of two maps, using the specified function to combine values for duplicate keys.

union :: forall v k. Ord k => Map k v -> Map k v -> Map k v

Compute the union of two maps, preferring values from the first map in the case of duplicate keys

toUnfoldableUnordered :: forall v k f. Unfoldable f => Map k v -> f (Tuple k v)

Convert a map to an unfoldable structure of key/value pairs

While this traversal is up to 10% faster in benchmarks than toUnfoldable, it leaks the underlying map stucture, making it only suitable for applications where order is irrelevant.

If you are unsure, use toUnfoldable

toUnfoldable :: forall v k f. Unfoldable f => Map k v -> f (Tuple k v)

Convert a map to an unfoldable structure of key/value pairs where the keys are in ascending order

submap :: forall v k. Ord k => Maybe k -> Maybe k -> Map k v -> Map k v

Returns a new map containing all entries of the given map which lie between a given lower and upper bound, treating Nothing as no bound i.e. including the smallest (or largest) key in the map, no matter how small (or large) it is. For example:

submap (Just 1) (Just 2)
  (fromFoldable [Tuple 0 "zero", Tuple 1 "one", Tuple 2 "two", Tuple 3 "three"])
  == fromFoldable [Tuple 1 "one", Tuple 2 "two"]

submap Nothing (Just 2)
  (fromFoldable [Tuple 0 "zero", Tuple 1 "one", Tuple 2 "two", Tuple 3 "three"])
  == fromFoldable [Tuple 0 "zero", Tuple 1 "one", Tuple 2 "two"]

The function is entirely specified by the following property:

Given any m :: Map k v, mmin :: Maybe k, mmax :: Maybe k, key :: k,
  let m' = submap mmin mmax m in
    if (maybe true (\min -> min <= key) mmin &&
        maybe true (\max -> max >= key) mmax)
      then lookup key m == lookup key m'
      else not (member key m')

size :: forall v k. Map k v -> Int

Calculate the number of key/value pairs in a map

singleton :: forall v k. k -> v -> Map k v

Create a map with one key/value pair

showTree :: forall v k. Show k => Show v => Map k v -> String

Render a Map as a String

pop :: forall v k. Ord k => k -> Map k v -> Maybe (Tuple v (Map k v))

Delete a key and its corresponding value from a map, returning the value as well as the subsequent map.

member :: forall v k. Ord k => k -> Map k v -> Boolean

Test if a key is a member of a map

mapMaybeWithKey :: forall b a k. Ord k => (k -> a -> Maybe b) -> Map k a -> Map k b

Applies a function to each key/value pair in a map, discarding entries where the function returns Nothing.

mapMaybe :: forall b a k. Ord k => (a -> Maybe b) -> Map k a -> Map k b

Applies a function to each value in a map, discarding entries where the function returns Nothing.

lookupLT :: forall v k. Ord k => k -> Map k v -> Maybe { key :: k, value :: v }

Look up a value for the greatest key less than the specified key

lookupLE :: forall v k. Ord k => k -> Map k v -> Maybe { key :: k, value :: v }

Look up a value for the specified key, or the greatest one less than it

lookupGT :: forall v k. Ord k => k -> Map k v -> Maybe { key :: k, value :: v }

Look up a value for the least key greater than the specified key

lookupGE :: forall v k. Ord k => k -> Map k v -> Maybe { key :: k, value :: v }

Look up a value for the specified key, or the least one greater than it

lookup :: forall v k. Ord k => k -> Map k v -> Maybe v

Look up a value for the specified key

isSubmap :: forall v k. Ord k => Eq v => Map k v -> Map k v -> Boolean

Test whether one map contains all of the keys and values contained in another map

isEmpty :: forall v k. Map k v -> Boolean

Test if a map is empty

intersectionWith :: forall c b a k. Ord k => (a -> b -> c) -> Map k a -> Map k b -> Map k c

Compute the intersection of two maps, using the specified function to combine values for duplicate keys.

intersection :: forall b a k. Ord k => Map k a -> Map k b -> Map k a

Compute the intersection of two maps, preferring values from the first map in the case of duplicate keys.

insertWith :: forall v k. Ord k => (v -> v -> v) -> k -> v -> Map k v -> Map k v

Inserts or updates a value with the given function.

The combining function is called with the existing value as the first argument and the new value as the second argument.

insert :: forall v k. Ord k => k -> v -> Map k v -> Map k v

Insert or replace a key/value pair in a map

fromFoldableWithIndex :: forall v k f. Ord k => FoldableWithIndex k f => f v -> Map k v

Convert any indexed foldable collection into a map.

fromFoldableWith :: forall v k f. Ord k => Foldable f => (v -> v -> v) -> f (Tuple k v) -> Map k v

Convert any foldable collection of key/value pairs to a map. On key collision, the values are configurably combined.

fromFoldable :: forall v k f. Ord k => Foldable f => f (Tuple k v) -> Map k v

Convert any foldable collection of key/value pairs to a map. On key collision, later values take precedence over earlier ones.

foldSubmap :: forall m v k. Ord k => Monoid m => Maybe k -> Maybe k -> (k -> v -> m) -> Map k v -> m

Fold over the entries of a given map where the key is between a lower and an upper bound. Passing Nothing as either the lower or upper bound argument means that the fold has no lower or upper bound, i.e. the fold starts from (or ends with) the smallest (or largest) key in the map.

foldSubmap (Just 1) (Just 2) (\_ v -> [v])
 (fromFoldable [Tuple 0 "zero", Tuple 1 "one", Tuple 2 "two", Tuple 3 "three"])
 == ["one", "two"]

foldSubmap Nothing (Just 2) (\_ v -> [v])
 (fromFoldable [Tuple 0 "zero", Tuple 1 "one", Tuple 2 "two", Tuple 3 "three"])
 == ["zero", "one", "two"]

findMin :: forall v k. Map k v -> Maybe { key :: k, value :: v }

Returns the pair with the least key

findMax :: forall v k. Map k v -> Maybe { key :: k, value :: v }

Returns the pair with the greatest key

filterWithKey :: forall v k. Ord k => (k -> v -> Boolean) -> Map k v -> Map k v

Filter out those key/value pairs of a map for which a predicate fails to hold.

filterKeys :: forall k. Ord k => (k -> Boolean) -> (Map k) ~> (Map k)

Filter out those key/value pairs of a map for which a predicate on the key fails to hold.

filter :: forall v k. Ord k => (v -> Boolean) -> Map k v -> Map k v

Filter out those key/value pairs of a map for which a predicate on the value fails to hold.

empty :: forall v k. Map k v

An empty map

difference :: forall w v k. Ord k => Map k v -> Map k w -> Map k v

Difference of two maps. Return elements of the first map where the keys do not exist in the second map.

delete :: forall v k. Ord k => k -> Map k v -> Map k v

Delete a key and its corresponding value from a map.

checkValid :: forall v k. Map k v -> Boolean

Check whether the underlying tree satisfies the 2-3 invariant

This function is provided for internal use.

alter :: forall v k. Ord k => (Maybe v -> Maybe v) -> k -> Map k v -> Map k v

Insert the value, delete a value, or update a value for a key in a map