Overview

• Admin.
• Exam 2 Questions.
• Lab.

Admin

• Today's writeup: 4 and 6.
• SHACS tells me that "there have been many students who have been seen or reported having the stomach flu which include the following symptoms: Fever, Nausea, Vomiting, Diarrhea, Headaches, Fatigue, Body Aches".
  • If you have these symptoms, "It is important to get plenty of rest and notify your faculty that you will not be attending classes until you are 24 hours without a fever."
  • If you have these symptoms and cannot manage them, go to SHACS.
  • If you need extra time on the exam because of the stomach flu, let me know.
• I brought food-like substances.
• I'll reserve time for general exam questions.
• Upcoming extra credit opportunities:
  • Any one Grinnell prize event this week.
  • Thursday extras this week: Reports from internships (I think)
  • Grinnell Town Hall Meeting, Nov 13 noon or 7:30, I believe
  • CS Table, Friday: TBD
  • CS Dept. Monday, 4:15: The Future of Our Curriculum

Exam Questions

• Cite!
• What is "no explicit recursion"? Don't write your own recursive procedure, but feel free to call a procedure like length or list-ref that's probably implemented recursively.

Lab

The following are all color trees "blue" (cons "blue" "red") (cons (cons "blue "red") "yellow") (cons "yellow" (cons "blue "red")) (cons (cons "yellow red") (cons "blue "red")) (cons (cons (cons "yellow "red") "white") (cons "blue "red"))

How I wanted you to write color-tree?

(define color-tree?
  (lambda (val)
    (or (color? val)
        (and (pair? val)
             (color-tree? (car val))
             (color-tree? (cdr val))))))