;; Personal library catalog system ofr NOVELS
;; All information for a book is stored on the plist of the book
;;
;; Notes:
;;
;; 1. Book names will be symbols -- e.g., pride-and-prejudice
;; 2. Author names will be strings -- e.g., "Jane Austin"
;; 3. Dates will be integers -- e.g., 1813
;; 4. Genres will be strings -- e.g., "comedy of manners"

;; The catalog is a global variable

(setf *catalog* ())

; This function adds a book (a symbol which is loaded with
; properties) to the catalog

(defun add (title author1 date1 genre1)
  (setf (get title 'author) author1)
  (setf (get title 'date) date1)
  (setf (get title 'genre) genre1)
  (setf *catalog* (cons title *catalog*))
)

; Three simple referencers

(defun author (title)
  (get title 'author)
)

(defun date (title)
  (get title 'date)
)

(defun genre (title)
  (get title 'genre)
)

; This function displays the catalog in the form of "crude" plists.
(defun dump-holdings ()
  (mapcar #'symbol-plist *catalog*)
)

; This function displays the catalog in a nice format
(defun display-holdings ()
  (display-holdings2 *catalog*)
)

; helper function for the function above
(defun display-holdings2 (l &aux item)
  (cond
    ((null l)
      t
    )
    (t
      (setf item (car l))
      (format t "Title: ~A Author: ~A Date: ~A Genre: ~A" item (author item) (date item) (genre item)) (terpri)
      (display-holdings2 (cdr l))
    )
  )
)