Homework 8 Clarifications/Help

Read the following requirements and clarifications regarding HW8.

2. Problem 10.2.4 from the text.

   Use these structures for phone-record:

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   ;; A phone-record is
   ;;   (make-phone-record name ph-num)
   ;; where name is a symbol, and
   '' ph-num is a number
   (define-struct phone-record (name ph-num))

   ;; A phone-directory is either:
   ;;   empty, or
   ;;   (cons a-phone-record a-phone-directory)
   ;; where a-phone-record is a phone-record, and
   ;; a-phone-directory is a phone-directory

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   Notice that for this problem a name is just a single name like
   'Tom, 'Dick, or 'Harry.  I.e. it is a single symbol.

   Notice also that you are to store a phone number as number, not a
   symbol.

   The functions you are to write, whose-number and phone-number, are to
   have their respective parameters in the orders indicated below:

   1.  whose-number is to take two parameters.  The phone number and then
   secondly the phone directory to be searched.

   2.  phone-number is to take two parameters.  The name and then
       secondly the phone directory to be searched.

   
   ASSUME that there are no duplicates of names and no duplicates of
   phone numbers in your directory.  Just base your result on the
   first match you find.  (You are not guaranteed a match.  Read on.)

   Also assume that when the name or phone number is not in the
   directory, you return the symbol 'not-found.  That is, when you
   search you will find a match occuring once or not at all.