Trying to run the program below (or any other one) gets the error message "Class 'Timer' does not have a main method"
which it obviously does. Any ideas what's wrong?

object Timer {
    def oncePerSecond(callback: () => unit) {
        while (true) { callback(); Thread sleep 1000 }
    }
    def timeFlies() {
        println("time flies like an arrow...")
    }
    def main(args: Array[String]) {
        oncePerSecond(timeFlies)
    }
}