“To iterate is human, to recurse divine.” -Peter DeutschRecursion is a natural idea. When humans perform repetitive tasks, we don't assign state variables, and we generally don't keep counters. We just keep doing the same thing over and over until we arrive at some kind of terminating condition. This “pattern” forms the basis of recursive programming.In “The Little Schemer” Friedman and Felleisen lay out the following basic pattern for writing recursive functions.Establish a terminating conditio...