sicp习题试解 (2.51)

; ======================================================================

;

; Structure and Interpretation of Computer Programs

; (trial answer to excercises)

;

; 计算机程序的构造和解释(习题试解)

;

; created: code17 08/20/05

; modified:

; (保持内容完整不变前提下，可以任意转载)

; ======================================================================

;; SICP No.2.51

;; a

(define (below painter1 painter2)

(lambda (frame)

((transform-painter painter1

(make-vect 0.0 0.0)

(make-vect 1.0 0.0)

(make-vect 0.0 0.5))

frame)

((transform-painter painter2

(make-vect 0.0 0.5)

(make-vect 1.0 0.5)

(make-vect 0.0 1.0))

frame)))

;; b

(define (below painter1 painter2)

(rotate180

(rotate270

(beside (rotate270 painter1)

(rotate270 painter2)))))