The Little Schemer F o u r t h E d i t i o n Daniel P. Friedman and Matthias Felleisen Foreword bf GenW J. s-.n.a The Ten Commandments The First Commandment When recurring on a list of atoms, lat, ask two questions about it: (null? lat) and else. When recurring on a number, n, ask two questions about it: (zero? n) and else. When recurring on a list of S-expressions, l, ask three question about it: (null? l), (atom? (car l)), and else. The Second Commandment Use cons to build lists. The Third Commandment The Fifth Commandment When building a value with + ,always use 0 for the value of the terminating line, for adding 0 does not change the value of an addition. When building a value with x, always use 1 for the value of the terminating line, for multiplying by 1 does not change the value of a multiplication. When building a value with cons, always consider () for the value of the terminating line. When building a list, describe the
