A dictionary mapping unique keys to values. The keys can be any type that can be converted to an elm 'comparable'.
This is helpful if you have keys that are really just a comparable underneath, but you want to keep them separate using the type system. For instance
type TagId
= TagId Int
type CustomerId
= CustomerId Int
emptyTagDict =
TDict.empty (\(TagId id) -> id) TagId String
emptyCustomerDict =
TDict.empty (\(CustomerId id) -> id) CustomerId String
So inserting a (tag,string) into an emptyTagDict works:
TDict.insert ( TagId 1, "some string of interest" ) emptyTagDict
But inserting a (tag,string) into an emptyCustomerDict doesn't:
TDict.insert ( TagId 1, "some string of interest" ) emptyCustomerDict
A dictionary of keys and values. Create a TDict with the empty
function.
empty : (k -> comparable) -> (comparable -> k) -> TDict k comparable val
Create an empty dictionary of keys and values. Requires two conversion functions: one from the key to comparable, and the other from comparable to key.
clear : TDict k comparable val -> TDict k comparable val
Remove all elements from the TDict
insert : k -> v -> TDict k comparable v -> TDict k comparable v
Insert a key-value pair into a dictionary. Replaces value when there is a collision.
update : k -> (Maybe v -> Maybe v) -> TDict k comparable v -> TDict k comparable v
Update the value of a dictionary for a specific key with a given function.
remove : k -> TDict k comparable val -> TDict k comparable val
Remove a key-value pair from a dictionary. If the key is not found, no changes are made.
isEmpty : TDict k comparable val -> Basics.Bool
Determine if a dictionary is empty.
member : k -> TDict k comparable v -> Basics.Bool
Determine if a key is in a dictionary.
get : k -> TDict k comparable v -> Maybe v
Get the value associated with a key. If the key is not found, return
Nothing
. This is useful when you are not sure if a key will be in the
dictionary.
size : TDict k comparable v -> Basics.Int
Determine the number of key-value pairs in the dictionary.
keys : TDict k comparable v -> List k
Get all of the keys in a dictionary, sorted from lowest to highest.
values : TDict k comparable v -> List v
Get all of the values in a dictionary, in the order of their keys.
toList : TDict k comparable v -> List ( k, v )
Convert a dictionary into an association list of key-value pairs, sorted by keys.
insertList : TDict k comparable v -> List ( k, v ) -> TDict k comparable v
Merge an association list into a dictionary.
map : (k -> a -> b) -> TDict k comparable a -> TDict k comparable b
Apply a function to all values in a dictionary.
foldl : (k -> v -> b -> b) -> b -> TDict k comparable v -> b
Fold over the key-value pairs in a dictionary, in order from lowest key to highest key.
foldr : (k -> v -> b -> b) -> b -> TDict k comparable v -> b
Fold over the key-value pairs in a dictionary, in order from highest key to lowest key.
filter : (k -> v -> Basics.Bool) -> TDict k comparable v -> TDict k comparable v
Keep a key-value pair when it satisfies a predicate.
partition : (k -> v -> Basics.Bool) -> TDict k comparable v -> ( TDict k comparable v, TDict k comparable v )
Partition a dictionary according to a predicate. The first dictionary contains all key-value pairs which satisfy the predicate, and the second contains the rest.
union : TDict k comparable v -> TDict k comparable v -> TDict k comparable v
Combine two dictionaries. If there is a collision, preference is given to the first dictionary.
intersect : TDict k comparable v -> TDict k comparable v -> TDict k comparable v
Keep a key-value pair when its key appears in the second dictionary. Preference is given to values in the first dictionary.
diff : TDict k comparable v -> TDict k comparable v -> TDict k comparable 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) -> TDict k comparable a -> TDict k comparable b -> result -> result
The most general way of combining two dictionaries. You provide three accumulators for when a given key appears:
You then traverse all the keys from lowest to highest, building up whatever you want.