GenericDict

type Dict k v

A dictionary of keys and values. Keys can be any type.

Build

empty : Dict k v

Create an empty dictionary.

singleton : (k -> String) -> k -> v -> Dict k v

Create a dictionary with one key-value pair.

insert : (k -> String) -> k -> v -> Dict k v -> Dict k v

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

update : (k -> String) -> k -> (Maybe v -> Maybe v) -> Dict k v -> Dict k v

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

remove : (k -> String) -> k -> Dict k v -> Dict k v

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

Query

isEmpty : Dict k v -> Bool

Determine if a dictionary is empty.

member : (k -> String) -> k -> Dict k v -> Bool

Determine if a key is in a dictionary.

get : (k -> String) -> k -> Dict k v -> Maybe v

Get the value associated with a key. Returns Nothing if the key is not found.

size : Dict k v -> Int

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

Lists

keys : Dict k v -> List k

Get all of the keys in a dictionary.

values : Dict k v -> List v

Get all of the values in a dictionary.

toList : Dict k v -> List ( k, v )

Convert a dictionary into an association list of key-value pairs.

fromList : (k -> String) -> List ( k, v ) -> Dict k v

Convert an association list into a dictionary.

Transform

map : (k -> a -> b) -> Dict k a -> Dict k b

Apply a function to all values in a dictionary.

fold : (k -> v -> b -> b) -> b -> Dict k v -> b

Fold over the key-value pairs in a dictionary.

filter : (k -> v -> Bool) -> Dict k v -> Dict k v

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

partition : (k -> v -> Bool) -> Dict k v -> ( Dict k v, Dict k v )

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 : Dict k v -> Dict k v -> Dict k v

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

intersect : Dict k v -> Dict k v -> Dict k v

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

diff : Dict k v -> Dict k v -> Dict k v

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

merge :

(k -> a -> result -> result)

-> (k -> a -> b -> result -> result)

-> (k -> b -> result -> result)

-> Dict k a

-> Dict k b

-> result

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

Only in the left dictionary.
In both dictionaries.
Only in the right dictionary.

You then traverse all the keys from lowest to highest, building up whatever you want.

Modules

GenericDict

edkv/elm-generic-dict/1.0.0