Quiz 2 Key, CS 257

1. Respectable plant-people of the planet Blorg have their names inscribed upon their trunks shortly after germination. When a purple Blorgian speaks someone's name, it adds a suffix "-OOK-OOK" to the name inscribed on their trunk. When a green Blorgian addresses someone, it adds a prefix "BLIP-" to their name if it starts with a "Z", adds the prefix "BLOP-" to their name if it starts with a "Q", and adds the honorific suffix "-ICHOR" if it ends with an "S".

   Define a function (BLORG-SPOKEN-NAME COLOR-OF-SPEAKER NAME-ON-TRUNK) which, given the color of the speaking Blorgian and the name inscribed on the trunk of the Blorgian being addressed, returns the name to be spoken.

   For example:
   

   Color of Speaking Blorgian	Name on Trunk of Blorgian Being Addressed	Name to be Spoken
   PURPLE	ZACH	ZACH-OOK-OOK
   GREEN	ZACH	BLIP-ZACH
   GREEN	ZAQS	BLIP-ZAQS-ICHOR
   GREEN	QUUX	BLOP-QUUX
   GREEN	QUIS	BLOP-QUIS-ICHOR
   GREEN	JIMMY	JIMMY
   PURPLE	JIMMY	JIMMY-OOK-OOK

   ---

   (define (blorg-spoken-name color name)
     (cond ((equal color 'purple)
            (word name '-ook-ook))
   	((equal color 'green)
   	 (word (cond ((equal? (first name) 'z) 'blip-)   
   		     ((equal? (first name) 'q) 'blop-)   
   		     (else ""))                          
   	       name                                      
   	       (if (equal? (last name) 's)
                      '-ichor
                      "")))))
   
   

2. Define a function (ADD-UP SEN) that, given a sentence of numbers, returns the sum of all the numbers in the sentence. For instance, (ADD-UP '(93)) = 93, (ADD-UP '(1 3 5)) = 9, and (ADD-UP '()) = 0.

   ---

   (define (add-up sen)
     (if (empty? sen)
         0
         (+ (first sen)
            (add-up (rest sen)))))
   

3. What values are printed when you type each of the following to Scheme?

   expression	result
   (or #f #f 'aye 'bee)	AYE
   (and #t #t 'aye 'bee)	BEE
   (sentence 1 2)	(1 2)
   '(sentence 1 2)	(SENTENCE 1 2)
   (word 12 13)	1213
   (first 98765)	9
   (first '(98 76 5))	98
   (butfirst '(98 76 5))	(76 5)
   (quote (and 1 2))	(AND 1 2)
   (not 'false)	#f

4. Rewrite the following using IF rather than COND.

   (define (utensil cuisine)
      (cond ((equal? cuisine 'chinese) 'chopsticks)
            ((equal? cuisine 'ethiopian) 'fingers)
            (else 'fork)))
   

   ---

   (define (utensil cuisine)
      (if (equal? cuisine 'chinese)
          'chopsticks
          (if (equal? cuisine 'ethiopian)
              'fingers
              'fork)))