Exercise 1.5. Ben Bitdiddle has invented a test to determine whether the interpreter he is faced
with is using applicative-order evaluation or normal-order evaluation. He defines the following two
procedures:
(define (p) (p))
(define (test x y)
(if (= x 0)
0
y))
Then he evaluates the expression
(test 0 (p))
What behavior will Ben observe with an interpreter that uses applicative-order evaluation? What
behavior will he observe with an interpreter that uses normal-order evaluation? Explain your
answer. (Assume that the evaluation rule for the special form if is the same whether the interpreter
is using normal or applicative order: The predicate expression is evaluated first, and the result
determines whether to evaluate the consequent or the alternative expression.)



answer: 
1.Normal Order 
  In this order, it will fully expand  and won't be evaluate until it is necessary. So it won't evaluate the (p), it will get the right answer.(return 0).


2.Applicative Order
  In this order, the interpreter will evaluate (p) when we call test. So it will call p over and over . It's just in a dead circulation.