The document discusses using recursive data definitions to represent payroll entries as structured data. It defines a payroll entry structure type with fields for an employee's name, SSN, position, hours worked, pay rate, current pay, and year-to-date pay. Examples are given of creating individual payroll entries. Functions are described for updating an entry's hours worked and pay fields, and for mapping a function over a list of payroll entries, such as to raise all employees' pay rates by a certain amount. The importance of recursive data definitions and interpretation in the definitions is emphasized.

1. Recursive Data Definitions EverywhereCS 5010 Program Design Paradigms “Bootcamp”Week 03, Lesson 2TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAA1

2. Lists of Structures(define-struct payroll-entry (name ssn position current-hrs-worked pay-rate current-pay ytd-pay));; A PayrollEntry is a ;; (make-payroll-entry ;; String Number String ;; Number NumberNumberNumber);; where:;; name is the employee's name;; ssn is the employee's Social Security Number;; position is the the employee's position;; current-hrs-worked is the number of hours the employee has worked ;; in the current pay period;; pay-rate is the employee's pay in $/hr;; current-pay is the amount the employee is to be paid;; for the current pay period;; ytd-pay is the employee's total pay for the current year;; through the current pay period.

3. Examples(define entry1 (make-payroll-entry "Joe" 123456789 "teaching assistant" 0 20.00 0 1000))(define entry2 (make-payroll-entry "Mitch" 987654321 "professor" 10 100.00 1000. 10000.))

4. ;; update-entry : PayRollEntry Number -> PayRollEntry;; produces a payroll entry like the given one, ;; except that current-hrs-worked is updated to the given ;; number, and current-pay and ytd-pay are updated;; accordingly.;; example:;(update-entry entry1 10) ;= (make-payroll-entry; "Joe" 123456789 "teaching assistant"; 200 20.00 400.0 1400)update-entry

5. update-entry (cont’d);; Design Strategy: structural decomposition on entry [PayrollEntry](define (update-entry entry hrs) (make-payroll-entry (payroll-entry-name entry) (payroll-entry-ssn entry) (payroll-entry-position entry) hrs (payroll-entry-pay-rate entry) (* hrs (payroll-entry-pay-rate entry)) ; the pay for ; this period (+ (payroll-entry-ytd-pay entry) (* hrs (payroll-entry-pay-rate entry)))))

6. Exercise:Observe that (* hrs (payroll-entry-pay-rate entry))occurs twice in the code. What information does this quantity represent?Design a function to compute this.Rewrite update-entry to use your new function.

7. But there are many people in our company!;; A ListOfPayrollEntries (LoPE) is one of;; -- empty;; -- (cons PayrollEntryLoPE);; A Payroll is a LoPE

8. Exercise:;; raise-all : Payroll * Number -> Payroll;; Produces a payroll like the given payroll, but with everyone's;; pay rate increased by the given number.;(raise-all (list entry1 entry2) 0.10);= (list; (make-payroll-entry ; "Joe" 123456789 "teaching assistant"; 0 22.00 0 1000); (make-payroll-entry; "Mitch" 987654321 "professor"; 10 110.00 1100. 10000.))What does the example show us that isn’t obvious from the purpose statement?

9. Exercise:;; rename-position : Payroll * String * String;; Given a payroll, an old position name, and a new position name,;; returns a payroll like the given one, except all entries matching ;; the old position name are updated.

10. An Example/Test;(rename-position ; (list entry1 entry2); "teaching assistant"; "grader");= (list; (make-payroll-entry ; "Joe" 123456789 "teaching assistant"; 0 20.00 0 1000); (make-payroll-entry; "Mitch" 987654321 "professor"; 10 100.00 1000. 10000.))This test is insufficient! How could you write an incorrect function that would still pass this test?

11. SummaryLists of structures occur all the timeImportant to have interpretation in the data defs!The recipe is your friend!Study the tests: always ask: how could a program pass the tests and still be wrong?