ballerina/lang.map Ballerina library

Applies a function each member of a map and returns a map of the result.

The resulting map will have the same keys as the argument map.

map<int> marks = {"Carl": 85, "Bob": 50, "Max": 60};
marks.map(m => m > 50) ⇒ {"Carl":true,"Bob":false,"Max":true}

Returns a map containing [key, member] pair as the value for each key.

{"Carl": 85, "Bob": 50}.entries() ⇒ {"Carl":["Carl",85],"Bob":["Bob",50]}

Selects the members from a map for which a function returns true.

map<int> marks = {"Carl": 85, "Bob": 50, "Max": 60};
marks.filter(m => m >= 60) ⇒ {"Carl":85,"Max":60}

Applies a function to each member of a map.

The parameter func is applied to each member of parameter m.

int total = 0;
{"Carl": 85, "Bob": 50, "Max": 60}.forEach(function (int m) {
    total += m;
});
total ⇒ 195

Returns the member of a map with given key.

This for use in a case where it is known that the map has a specific key, and accordingly panics if parameter m does not have a member with parameter k key.

map<int> marks = {"Carl": 85, "Bob": 50, "Max": 60};

marks.get("Carl") ⇒ 85

marks.get("John") ⇒ panic

Tests whether a map value has a member with a given key.

map<int> marks = {"Carl": 85, "Bob": 50, "Max": 60};

marks.hasKey("Carl") ⇒ true

marks.hasKey("John") ⇒ false

Returns an iterator over a map.

The iterator will iterate over the members of the map not the keys. The function entries can be used to iterate over the keys and members together. The function keys can be used to iterator over just the keys.

object {
    public isolated function next() returns record {|int value;|}?;
} iterator = {"Carl": 85, "Bob": 50, "Max": 60}.iterator();
iterator.next() ⇒ {"value":85}

Returns a list of all the keys of a map.

{"Carl": 85, "Bob": 50, "Max": 60}.keys() ⇒ ["Carl","Bob","Max"]

Returns number of members of a map.

{"Carl": 85, "Bob": 50, "Max": 60}.length() ⇒ 3

Combines the members of a map using a combining function.

The combining function takes the combined value so far and a member of the map, and returns a new combined value.

map<int> marks = {"Carl": 85, "Bob": 50, "Max": 60};
marks.reduce(isolated function (int total, int next) returns int => total + next, 0) ⇒ 195

Removes a member of a map.

This removes the member of parameter m with key parameter k and returns it. It panics if there is no such member.

map<int> marks = {"Carl": 85, "Bob": 50, "Max": 60};

marks.remove("Carl") ⇒ 85
marks ⇒ {"Bob":50,"Max":60}

marks.remove("John") ⇒ panic

Removes all members of a map.

This panics if any member cannot be removed.

map<int> marks = {"Carl": 85, "Bob": 50, "Max": 60};
marks.removeAll();
marks ⇒ {}

map<int> values = <record {|int x; int y;|}> {x: 10, y: 20};
values.removeAll() ⇒ panic;

Removes a member of a map with a given key, if the map has member with the key.

If parameter m has a member with key parameter k, it removes and returns it; otherwise it returns ().

map<int> marks = {"Carl": 85, "Bob": 50, "Max": 60};

marks.removeIfHasKey("Carl") ⇒ 85
marks ⇒ {"Bob":50,"Max":60}

marks.removeIfHasKey("John") is () ⇒ true

Returns a list of all the members of a map.

{"Carl": 85, "Bob": 50, "Max": 60}.toArray() ⇒ [85,50,60]