Lecture #1: In Class Activity

Solution Key

Problem 1

  1. ;; Error: Unbound variable 1
  2. (1 2 3)
  3. (HELLO WORLD)
  4. ;; Error: Unbound function 'Hello
  5. WUMPUS
  6. ;; Error: Unbound variable Wumpus

Problem 2

(+ 31 (* 3 2) (/ 8 2) 9)
(+ 31 6 (/ 8 2) 9)
(+ 31 6 4 9)
50

Problem 3

  1. A
  2. B
  3. B
  4. A

Problem 4

Evaluation begins as (if attempts to formulate it's arguments by evaluating the (or) statement. (listp 1) evaluates to nil, (listp 2) evaluates to nil, (null nil) evaluates to t. Evaluation stops there; (not nil) is never evaluated. Since the (or) expression returned true, the next argument to (if) (the then clause) is evaluted: (listp '(1 2 3)) returns t. The entire code expression therefore returns t.

Problem 5 

> (defun hypo (x y) 
   (sqrt (+ (* x x) 
            (* y y)
         )
   )
  )
HYPO
> (hypo 3 4)
5.0
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