yao2030

;; 
(define (accumulate op init seq)
  (if (null? seq)
      init
      (op (car seq)
	  (accumulate op init (cdr seq)))))
;;
(define (accumulate-n op init seqs)
  (if (null? (car seqs))
      '()

yao2030

(define (last-pair list1)
  (if (= (length list1) 1)
      (car list1)
      (last-pair (cdr list1))))
(define (but-last list1)
  (if (= (length list1) 1)
      '()
      (cons (car list1) (but-last (cdr list1)))))
(define (reverse x)
  (if (null? x)

yao2030

(define (fold-left op initial sequence)
  (define (iter result rest)
    (if (null? rest)
	result
	(iter (op result (car rest))
	      (cdr rest))))
  (iter initial sequence))
(define fold-right accumulate)

(define (reverse seq)

yao2030

(define (up-split painter n)
  (if (= n 0)
      painter
      (let ((smaller (up-split painter (- n 1))))
	(below painter (beside smaller smaller)))))
      

yao2030

(define (split op1 op2)
  (lambda (painter n)
    (if (= n 0)
	painter
	(let ((smaller ((split op1 op2) painter (- n 1))))
	  (op1 painter (op2 smaller smaller))))))

yao2030

(define (make-vect x y)
  (cons x y))
(define (xcor-vect v)
  (car v))
(define (ycor-vect v)
  (cdr v))
(define (add-vect v1 v2)
  (make-vect (+ (xcor-vect v1) (xcor-vect v2))
	     (+ (ycor-vect v1) (ycor-vect v2))))
(define (sub-vect v1 v2)

yao2030

(define (equal? list1 list2)
	(cond ((null? list1) (null? list2))
	      ((null? list2) #f)
	      ((eq? list1 list2) #t)
	      ((eq? (car list1) (car list2)) (equal? (cdr list1) (cdr list2)))
	      (else #f)))

yao2030

1. Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp
2. Code: The Hidden Language of Computer Hardware and Software
3. An introduction to algorithms
4. Artificial Intelligence: a modern approach
5. ON LISP
6. ANSI COMMON LISP
7. LISP IN SMALL PIECES
8. THE LITTLE LISPER
9. THE SEASONED SCHEMER

yao2030

(define (=number? exp num)
  (and (number? exp) (= exp num)))

(define (variable? x) (symbol? x))

(define (same-variable? a b)
  (and (variable? a) (variable? b) (eq? a b)))

(define (make-sum a1 a2)
  (cond ((=number? a1 0) a2)

yao2030

;;; SICP 2.58 part.b
;;;
;; sum
(define (make-sum a1 a2)
  (cond ((and (number? a1) (number? a2)) (+ a1 a2))
        ((=number? a1 0) a2)
	((=number? a2 0) a1)
	(else (list  a1 '+ a2))))
(define (sum? x)
  (and (pair? x) (eq? (cadr x) '+)))