(define (wrap-in-p str)
  (quasiquote (p (unquote str))))

(define (wrap-in-p2 str)
  (quote (p str)))

(define (wip str)
  `(p ,str))

(define (format-entry-as-html author title collection year)
  `(p (b ,author)
      (quote ,title)
      (i ,collection)
      (b ,year)
      "."))

(define (my-gcd x y)
  (let ((z (modulo x y)))
    (if (= z 0)
        y
        (my-gcd y z))))

(print-struct #t)
(define-struct heap-leaf () (make-inspector))
(define-struct heap-node (elt left# right# left right) (make-inspector))

(define (heap-add new-elt heap)
  (if (heap-leaf? heap)
      (make-heap-node new-elt 0 0 (make-heap-leaf) (make-heap-leaf))
      (let ((old-elt (heap-node-elt heap))
            (left# (heap-node-left# heap))
            (right# (heap-node-right# heap)))
        (let ((this (if (> old-elt new-elt) old-elt new-elt))
              (next (if (> old-elt new-elt) new-elt old-elt)))
          (if (> left# right#)
              (make-heap-node this left# (+ right# 1) 
                              (heap-node-left heap)
                              (heap-add next (heap-node-right heap)))
              (make-heap-node this (+ left# 1) right#
                              (heap-add next (heap-node-left heap))
                              (heap-node-right heap)))))))

(define (heap-empty? heap)
  (heap-leaf? heap))

(define (heap-pop heap)
  (if (heap-leaf? heap)
      (error "heap is empty")
      (let ((elt (heap-node-elt heap))
            (left# (heap-node-left# heap))
            (right# (heap-node-right# heap))
            (left (heap-node-left heap))
            (right (heap-node-right heap)))
        (cond 
          ((and (= left# 0) (= right# 0))
           (cons elt (make-heap-leaf)))
          
          ((or (= right# 0) 
               (and (> left# 0) (> (heap-node-elt left) (heap-node-elt right))))
           (let ((top-and-heap (heap-pop left)))
             (cons elt (make-heap-node (car top-and-heap)
                                       (- left# 1)
                                       right#
                                       (cdr top-and-heap)
                                       right))))
          (else
           (let ((top-and-heap (heap-pop right)))
             (cons elt (make-heap-node (car top-and-heap)
                                       left#
                                       (- right# 1)
                                       left
                                       (cdr top-and-heap)))))))))


(define h0 (make-heap-leaf))
(define h1 (heap-add 53 h0))
(define h2 (heap-add 17 h1))
(define h3 (heap-add 189 h2))
(define h4 (heap-add 7 h3))
(define h5 (heap-add 80 h4))
(define eh6 (heap-pop h5))
(define e1 (car eh6))
(define h6 (cdr eh6))
(define eh7 (heap-pop h6))
(define e2 (car eh7))
(define h7 (cdr eh7))
(define eh8 (heap-pop h7))
(define e3 (car eh8))
(define h8 (cdr eh8))