An example of a simple main program loop written in an impOS-friendly way.

loop.device.nut

function loop() {
    // Get an integer reading from the imp's light sensor and relay it via UART
    uart57.write("Current light level is: " + hardware.lightlevel() + "\r\n");

    // Set the imp to check again in two seconds' time
    imp.wakeup(2.0, loop);
}

// Start of program
// Initiate main loop
loop();