Notes on the Exercises

• Exercise 7.24: This exercise requires that you write the procedure movies-satisfying. The second and third tests require that you also write the filter predicate director-is-actor?.

• Exercise 7.26: Self-explanatory.

• Exercise 7.27: This exercise just asks you to run the query loop. Since it is tedious to repeatedly type the same queries in the interaction window, the test file automates the running of the query loop through the query-test procedure provided by the movie-test-utilities module. Testing for exercises 7.28 and 7.25 follows the same approach.

• Exercise 7.28: Note how the test for this exercise defines the movie pattern/action list by separately defining a director-action procedure that utilizes the-only-element-in. The test makes the same queries as for exercise 7.27, but the responses give just the movie's director, not the list containing the movie's director as in 7.27.

• Exercise 7.25: The test for this exercise adds to the movie pattern/action list by using action procedures that you must define, as in exercise 7.28.