Dict1 = Dict2 = dict(Key, Value)

Appends a new Value to the current list of values associated with Key.

Examples

1> Dict0 = dict:from_list([{a,[]}]).
2> Dict1 = dict:append(a, 1, Dict0).
3> dict:to_list(Dict1).
[{a,[1]}]
4> Dict2 = dict:append(a, 10, Dict1).
5> dict:to_list(Dict2).
[{a,[1,10]}]

Dict1 = Dict2 = dict(Key, Value)

Appends a list of values ValList to the current list of values associated with Key.

An exception is generated if the initial value associated with Key is not a list of values.

Examples

1> Dict0 = dict:from_list([{a,[]}]).
2> Dict1 = dict:append_list(a, [1,2,3], Dict0).
3> dict:to_list(Dict1).
[{a,[1,2,3]}]

Dict1 = Dict2 = dict(Key, Value)

Erases an item with a given key from a dictionary.

Examples

1> Dict0 = dict:from_list([{2,b},{1,a}]).
2> Dict1 = dict:erase(2, Dict0).
3> dict:to_list(Dict1).
[{1,a}]
4> Dict2 = dict:erase(99, Dict0).

Returns the value associated with Key in dictionary Dict.

This function assumes that Key is present in dictionary Dict, and an exception is generated if Key is not in the dictionary.

Examples

1> Dict = dict:from_list([{2,b},{1,a}]).
2> dict:fetch(1, Dict).
a

Keys = [Key]

Returns a list of all keys in dictionary Dict.

Examples

1> Dict = dict:from_list([{2,b},{1,a}]).
2> lists:sort(dict:fetch_keys(Dict)).
[1,2]

Pred = fun((Key, Value) -> boolean())

Dict1 = Dict2 = dict(Key, Value)

Returns a dictionary of all keys and values in Dict1 for which Pred(Key, Value) is true.

Examples

1> Dict0 = dict:from_list([{a,1},{b,2},{c,3}]).
2> Dict1 = dict:filter(fun(_, V) -> V rem 2 =:= 1 end, Dict0).
3> lists:sort(dict:to_list(Dict1)).
[{a,1},{c,3}]

Searches for a key in dictionary Dict.

Returns {ok, Value}, where Value is the value associated with Key, or error if the key is not present in the dictionary.

Examples

1> Dict = dict:from_list([{2,b},{1,a}]).
2> dict:find(1, Dict).
{ok,a}
3> dict:find(99, Dict).
error

Fun = fun((Key, Value, AccIn) -> AccOut)

Acc0 = Acc1 = AccIn = AccOut = Acc

Dict = dict(Key, Value)

Calls Fun on successive keys and values of dictionary Dict together with an extra argument Acc (short for accumulator).

Fun must return a new accumulator that is passed to the next call. Acc0 is returned if the dictionary is empty.

The evaluation order is undefined.

Examples

1> Dict0 = dict:from_list([{a,1},{b,2},{c,3}]).
2> dict:fold(fun(_, N, Acc) -> Acc + N end, 0, Dict0).
6

Dict = dict(Key, Value)

Converts the Key-Value list List to dictionary Dict.

Examples

1> Dict = dict:from_list([{2,b},{1,a}]).
2> lists:sort(dict:to_list(Dict)).
[{1,a},{2,b}]

Returns true if dictionary Dict has no elements; otherwise returns false.

Examples

1> Dict = dict:new().
2> dict:is_empty(Dict).
true

Tests whether Key is contained in dictionary Dict.

Examples

1> Dict = dict:from_list([{count,0}]).
2> dict:is_key(count, Dict).
true
3> dict:is_key(table, Dict).
false

Dict2 = dict(Key, Value2)

Calls Fun on successive keys and values of dictionary Dict1 to return a new value for each key.

The evaluation order is undefined.

Examples

1> Dict0 = dict:from_list([{a,1},{b,2},{c,3}]).
2> Dict1 = dict:map(fun(_, V) -> 2 * V end, Dict0).
3> lists:sort(dict:to_list(Dict1)).
[{a,2},{b,4},{c,6}]

Fun = fun((Key, Value1, Value2) -> Value)

Dict1 = dict(Key, Value1)

Dict2 = dict(Key, Value2)

Dict3 = dict(Key, Value)

Merges two dictionaries, Dict1 and Dict2, to create a new dictionary.

All the Key-Value pairs from both dictionaries are included in the new dictionary. If a key occurs in both dictionaries, Fun is called with the key and both values to return a new value.

Examples

1> Dict0 = dict:from_list([{a,1},{b,2}]).
2> Dict1 = dict:from_list([{b,7},{c,99}]).
3> Dict2 = dict:merge(fun(_, V1, V2) -> V1 + V2 end, Dict0, Dict1).
4> lists:sort(dict:to_list(Dict2)).
[{a,1},{b,9},{c,99}]

Creates a new dictionary.

Examples

1> dict:new().

Returns the number of elements in dictionary Dict.

Examples

1> Dict = dict:from_list([{2,b},{1,a}]).
2> dict:size(Dict).
2

Dict1 = Dict2 = dict(Key, Value)

Stores a Key-Value pair in dictionary Dict2.

If Key already exists in Dict1, the associated value is replaced by Value.

Examples

1> Dict0 = dict:new().
2> Dict1 = dict:store(name, arne, Dict0).
3> dict:to_list(Dict1).
[{name,arne}]
4> Dict2 = dict:store(name, kalle, Dict1).
5> dict:to_list(Dict2).
[{name,kalle}]

Key = Value = term()

Dict = Dict1 = dict(Key, Value)

Result = {Value, Dict1} | error

This function returns a value from dictionary and a new dictionary without this value.

Returns error if the key is not present in the dictionary.

Examples

1> Dict0 = dict:from_list([{2,b},{1,a}]).
2> {V, Dict2} = dict:take(1, Dict0).
3> V.
a
4> dict:to_list(Dict2).
[{2,b}]

List = [{Key, Value}]

Converts a dictionary to a list representation.

Examples

1> Dict = dict:from_list([{2,b},{1,a}]).
2> lists:sort(dict:to_list(Dict)).
[{1,a},{2,b}]

Fun = fun((Value1 :: Value) -> Value2 :: Value)

Dict1 = Dict2 = dict(Key, Value)

Updates a value in a dictionary by calling Fun on the value to get a new value.

Examples

1> Dict0 = dict:from_list([{a,10}]).
2> Dict1 = dict:update(a, fun(N) -> N + 1 end, Dict0).
3> dict:to_list(Dict1).
[{a,11}]

An exception is generated if Key is not present in the dictionary.

Fun = fun((Value1 :: Value) -> Value2 :: Value)

Initial = Value

Dict1 = Dict2 = dict(Key, Value)

Updates a value in a dictionary by calling Fun on the value to get a new value.

If Key is not present in the dictionary, Initial is stored as the first value.

Examples

1> Dict0 = dict:new().
2> Inc = fun(N) -> N + 1 end.
3> Dict1 = dict:update(a, Inc, 0, Dict0).
4> dict:to_list(Dict1).
[{a,0}]
5> Dict2 = dict:update(a, Inc, 0, Dict1).
6> dict:to_list(Dict2).
[{a,1}]

Dict1 = Dict2 = dict(Key, Value)

Adds Increment to the value associated with Key and stores this value.

If Key is not present in the dictionary, Increment is stored as the first value.

Examples

1> Dict0 = dict:new().
2> Dict1 = dict:update_counter(a, 10, Dict0).
3> dict:to_list(Dict1).
[{a,10}]
4> Dict2 = dict:update_counter(a, 10, Dict1).
5> dict:to_list(Dict2).
[{a,20}]