Events

Events are objects that allow you to attach callback functions, which are triggered when the event is invoked.

Creating events

Events are created using the keyword event as an expression. You can invoke an event simply by calling it like a function:

export message = event;

func main() {
    message("Hello World");
}

Handling events

To handle an event, you can define a callback using the event keyword again, this time as a declaration.

import console;
import message;

event message(msg) {
    console.print("Received: ", msg);
}

When the event message is triggered (as shown in the previous example), all callbacks registered for it will be executed with the given arguments.

Filtering Parameters

You can restrict when a callback is executed by specifying expected values for the parameters. This allows you to respond only to specific cases.

import console;
import message;

event message(msg ["hello", "world"]) {
    console.print("Received special case: ", msg);
}

In the example above, the callback is triggered only when msg is "hello" or "world".