Run a function forever, until specifically cancelled.

Example:

// Imports
import forever from "https://deno.land/x/forever/mod.ts";
import { Event } from "https://deno.land/x/subscription/mod.ts";

// Create an interrupted event.
const oninterrupt = new Event();

// Run a function forever without disturbing
// the current context.
const context = forever(async oncancel => {
    // Get the interrupt signal stream from Deno.
    const signal = Deno.signals.interrupt();
    
    // Subscribe for the cancel event and
    // dispose the signal stream when event is
    // fired.
    oncancel.subscribeOnce(() => signal.dispose());
    
    try {
        // Get the interruption events.
        for await (const _ of signal)
            // Fire the interruption event.
            await oninterrupt.dispatch();
    } catch (error) { }
});

// In case the forever function throws, listen
// for any errors by subscribing to the error
// event.
context.onerror.subscribe(console.error);

// Subscribe to the interruption event.
oninterrupt.subscribe(async () => {
    // Print out that the program was interrupted.
    console.log("Interrupted!");
    
    // Just for testing, set a timeout for 2
    // seconds to cancel the forever function.
    setTimeout(async () => {
        // Cancel.
        await context.cancel();
    }, 2000);
});