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Announcing Ballerina 2201.5.0 (Swan Lake Update 5)

Ballerina Team
15 April 2023

We are excited to announce the fifth update release of Ballerina Swan Lake, Ballerina 2201.5.0 (Swan Lake Update 5). In addition to the existing macOS installer, this release includes a new installer specifically designed for installing Ballerina on your macOS-ARM platforms.

As the key highlight of this release, now, you can use regular expressions in Ballerina code via the new lang.regexp library as shown in the example below.

import ballerina/lang.regexp;
import ballerina/io;

public function main() {
    string:RegExp emailRegex = re `[A-Za-z]+@[A-Za-z]+\.[A-Za-z]{2,}`;
    boolean validEmail = emailRegex.isFullMatch("");
    io:println(validEmail); // Prints “true”.

    regexp:RegExp commaSeparator = re `,`;
    string[] names = commaSeparator.split("Bob,Frank,Will,Jack");
    io:println(names); // Prints “["Bob","Frank","Will","Jack"]”.

    int patternCount = re `[bB].tt[a-z]*`.findAll("Butter was bought by Betty but the butter was bitter.").length();
    io:println(patternCount); // Prints “4”.

    string result = regexp:replaceAll(re `0+`, "10010011", "*");
    io:println(result); // Prints “1*1*11”.

Also, a new range function has been introduced in the lang library, which can be used to iterate over a range of integers with a specified step as the difference between two successive integers.

import ballerina/io;

public function main() {
    // Prints all even numbers from zero (inclusive) to 6(exclusive)
    // `start` is 0, `end` is 6, and `step` is 2.
    foreach int i in int:range(0, 6, 2) {

Furthermore, now, you can mark a specific version of a package as deprecated in Ballerina Central with the new bal deprecate command.

$ bal deprecate ballerina/io:1.1.1 --message="This package is deprecated due to a security vulnerability."

Similarly, you can undeprecate a version of a package with the --undo option.

$ bal deprecate ballerina/io:1.1.1 --undo

The BindGen tool is also enhanced to support handling Java null values via options passed to the bal bindgen command.

Beyond these highlights, the release includes numerous other notable additions and improvements to the language, runtime, standard library, and tooling. Further details about these enhancements are provided below.

  • The main function of a Ballerina program now accepts function parameters of built-in subtypes, which can be passed as command-line arguments.
  • Configurable variables of union types now accept structural values with ambiguous inherent types.
  • The http standard library now supports specifying a tuple type as the return type of service resource methods and having subtypes of string|int|float|decimal|boolean as client resource path parameter types.
  • The @http:Payload annotation is now optional for basic structured subtypes of anydata in HTTP resource methods.
    import ballerina/http;
    type Album readonly & record {|
        string title;
        string artist;
    table<Album> key(title) albums = table [];
    service / on new http:Listener(9090) {
        // No need to have the `http:Payload` annotation here.
        resource function post albums(Album album) returns Album {
            return album;
  • The graphql library is now enriched with a new feature to enable having GraphQL services as subgraphs in a GraphQL federation supergraph.

To learn more about the specific changes and improvements included in Swan Lake Update 5, see the release note.

We would like to thank the Ballerina community for their invaluable feedback and support in shaping it into what it is today. We look forward to your continued involvement in our efforts to improve the Ballerina language.

Cheers, The Ballerina Team