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Daml module

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DA.Map

Note: This is only supported in Daml-LF 1.11 or later.

Daml
ModuleDA.Map
Latest release3.5.9

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Functions

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fromList

fromList : Ord k => [(k, v)] -> Map k v Create a map from a list of key/value pairs.

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fromListWithL

fromListWithL : Ord k => (v -> v -> v) -> [(k, v)] -> Map k v Create a map from a list of key/value pairs with a combining function. The combining function is only used when a key appears multiple times in the list and it takes two arguments: the first one is the new value being inserted at that key and the second one is the value accumulated so far at that key. Examples:

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fromListWithR

fromListWithR : Ord k => (v -> v -> v) -> [(k, v)] -> Map k v Create a map from a list of key/value pairs like fromListWithL with the combining function flipped. Examples:

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fromListWith

fromListWith : Ord k => (v -> v -> v) -> [(k, v)] -> Map k v
Deprecated: Daml compatibility helper, use ‘fromListWithR’ instead of ‘fromListWith’

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keys

keys : Map k v -> [k] Get the list of keys in the map. Keys are sorted according to the built-in order for the type k, which matches the Ord k instance when using deriving Ord.

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values

values : Map k v -> [v] Get the list of values in the map. These will be in the same order as their respective keys from M.keys.

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toList

toList : Map k v -> [(k, v)] Convert the map to a list of key/value pairs. These will be ordered by key, as in M.keys.

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empty

empty : Map k v The empty map.

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size

size : Map k v -> Int Number of elements in the map.

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null

null : Map k v -> Bool Is the map empty?

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lookup

lookup : Ord k => k -> Map k v -> Optional v Lookup the value at a key in the map.

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member

member : Ord k => k -> Map k v -> Bool Is the key a member of the map?

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filter

filter : Ord k => (v -> Bool) -> Map k v -> Map k v Filter the Map using a predicate: keep only the entries where the value satisfies the predicate.

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filterWithKey

filterWithKey : Ord k => (k -> v -> Bool) -> Map k v -> Map k v Filter the Map using a predicate: keep only the entries which satisfy the predicate.

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delete

delete : Ord k => k -> Map k v -> Map k v Delete a key and its value from the map. When the key is not a member of the map, the original map is returned.

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singleton

singleton : Ord k => k -> v -> Map k v Create a singleton map.

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insert

insert : Ord k => k -> v -> Map k v -> Map k v Insert a new key/value pair in the map. If the key is already present in the map, the associated value is replaced with the supplied value.

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insertWith

insertWith : Ord k => (v -> v -> v) -> k -> v -> Map k v -> Map k v Insert a new key/value pair in the map. If the key is already present in the map, it is combined with the previous value using the given function f new_value old_value.

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alter

alter : Ord k => (Optional v -> Optional v) -> k -> Map k v -> Map k v Update the value in m at k with f, inserting or deleting as required. f will be called with either the value at k, or None if absent; f can return Some with a new value to be inserted in m (replacing the old value if there was one), or None to remove any k association m may have. Some implications of this behavior: alter identity k = identity alter g k . alter f k = alter (g . f) k alter (_ -> Some v) k = insert k v alter (_ -> None) = delete

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union

union : Ord k => Map k v -> Map k v -> Map k v The union of two maps, preferring the first map when equal keys are encountered.

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unionWith

unionWith : Ord k => (v -> v -> v) -> Map k v -> Map k v -> Map k v The union of two maps using the combining function to merge values that exist in both maps.

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merge

merge : Ord k => (k -> a -> Optional c) -> (k -> b -> Optional c) -> (k -> a -> b -> Optional c) -> Map k a -> Map k b -> Map k c Combine two maps, using separate functions based on whether a key appears only in the first map, only in the second map, or appears in both maps.

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Orphan Typeclass Instances