opvasger / comparable / Comparable.Dict

A dictionary mapping unique keys to values. The keys can be any type.

Dictionaries


type Dict key value

A dictionary of keys and values.

Compare

equals : Dict key value -> Dict key value -> Basics.Bool

Determine if two dictionaries contain the same entries.

Build

empty : Dict key value

Create an empty dictionary.

singleton : key -> value -> Dict key value

Create a dictionary with one key-value pair.

insert : Comparable key -> key -> value -> Dict key value -> Dict key value

Insert a key-value pair into a dictionary. Replaces value when there is a collision.

update : Comparable key -> key -> (Maybe value -> Maybe value) -> Dict key value -> Dict key value

Update the value of a dictionary for a specific key with a given function.

remove : Comparable key -> key -> Dict key value -> Dict key value

Remove a key-value pair from a dictionary. If the key is not found, no changes are made.

Query

isEmpty : Dict key value -> Basics.Bool

Determine if a dictionary is empty.

member : Comparable key -> key -> Dict key value -> Basics.Bool

Determine if a key is in a dictionary.

get : Comparable key -> key -> Dict key value -> Maybe value

Get the value associated with a key.

size : Dict key value -> Basics.Int

Determine the number of key-value pairs in the dictionary.

List

keys : Dict key value -> List key

Get all of the keys in a dictionary, sorted from lowest to highest.

values : Dict key value -> List value

Get all of the values in a dictionary, in the compare of their keys.

toList : Dict key value -> List ( key, value )

Convert a dictionary into an association list of key-value pairs, sorted by keys.

fromList : Comparable key -> List ( key, value ) -> Dict key value

Convert an association list into a dictionary.

Transform

map : (key -> value -> otherValue) -> Dict key value -> Dict key otherValue

Apply a function to all values in a dictionary.

foldl : (key -> value -> accumulator -> accumulator) -> accumulator -> Dict key value -> accumulator

Fold over the key-value pairs in a dictionary from lowest key to highest key.

foldr : (key -> value -> accumulator -> accumulator) -> accumulator -> Dict key value -> accumulator

Fold over the key-value pairs in a dictionary from highest key to lowest key.

filter : Comparable key -> (key -> value -> Basics.Bool) -> Dict key value -> Dict key value

Keep only the key-value pairs that pass the given test.

partition : Comparable key -> (key -> value -> Basics.Bool) -> Dict key value -> ( Dict key value, Dict key value )

Partition a dictionary according to some test. The first dictionary contains all key-value pairs which passed the test, and the second contains the pairs that did not.

Combine

union : Comparable key -> Dict key value -> Dict key value -> Dict key value

Combine two dictionaries. If there is a collision, preference is given to the first dictionary.

intersect : Comparable key -> Dict key value -> Dict key value -> Dict key value

Keep a key-value pair when its key appears in the second dictionary. Preference is given to values in the first dictionary.

diff : Comparable key -> Dict key value -> Dict key otherValue -> Dict key value

Keep a key-value pair when its key does not appear in the second dictionary.

merge : Comparable key -> (key -> value -> result -> result) -> (key -> value -> otherValue -> result -> result) -> (key -> otherValue -> result -> result) -> Dict key value -> Dict key otherValue -> result -> result

The most general way of combining two dictionaries. You provide three accumulators for when a given key appears:

  1. Only in the left dictionary.
  2. In both dictionaries.
  3. Only in the right dictionary. You then traverse all the keys from lowest to highest, building up whatever you want.