1. Evaluate the file lab8.scm. Take a look at the function make-account. This function creates an object which we will refer to as an account. This object has a local state which is the balance. The initial value of the balance is entered as an argument to make-account. Notice that this object is actually the procedure dispatch.

Try defining two objects with make-account:
        (define acct1 (make-account 100))
        (define acct2 (make-account 200))

What happens when we ask scheme for the value of acct1?
What happens when we enter (acct1 ‘withdraw)? Why did this happen?

Try the following:
        ((acct1 ‘withdraw) 50)
        ((acct1 ‘deposit) 40)
        ((acct2 ‘withdraw) 10)

2. In software-testing applications it is useful to be able to count the number of times a given function f is called during the course of a computation. We may do so by creating an object which has a local state which is a counter. If the input to our object is the special symbol ‘how-many-calls?, then it returns the value of the counter. If the input is the special symbol ‘reset-count, then the counter is reset to zero. For any other input, the object returns the result of calling f on that input and increments the counter.

For example, we could make a monitored version of the sqrt function:

Þ (define s (make-monitored sqrt))
Þ (s 100)
10
Þ (s ‘how-many-calls?)
1

3. Email your files containing the assignments to jzimmerm@goucher.edu.