remove debug code

chapter2/sicp_2_5.rkt

@@ -0,0 +1,63 @@
+;; 2.5  Systems with Generic Operations
+
+;; 2.5.1  Generic Arithmetic Operations
+
+(define (add x y) (apply-generic 'add x y))
+(define (sub x y) (apply-generic 'sub x y))
+(define (mul x y) (apply-generic 'mul x y))
+(define (div x y) (apply-generic 'div x y))
+
+(define (install-scheme-number-package)
+  (define (tag x)
+    (attach-tag 'scheme-number x))    
+  (put 'add '(scheme-number scheme-number)
+       (lambda (x y) (tag (+ x y))))
+  (put 'sub '(scheme-number scheme-number)
+       (lambda (x y) (tag (- x y))))
+  (put 'mul '(scheme-number scheme-number)
+       (lambda (x y) (tag (* x y))))
+  (put 'div '(scheme-number scheme-number)
+       (lambda (x y) (tag (/ x y))))
+  (put 'make 'scheme-number
+       (lambda (x) (tag x)))
+  'done)
+
+(define (make-scheme-number n)
+  ((get 'make 'scheme-number) n))
+
+(define (install-rational-package)
+  ;; internal procedures
+  (define (numer x) (car x))
+  (define (denom x) (cdr x))
+  (define (make-rat n d)
+    (let ((g (gcd n d)))
+      (cons (/ n g) (/ d g))))
+  (define (add-rat x y)
+    (make-rat (+ (* (numer x) (denom y))
+                 (* (numer y) (denom x)))
+              (* (denom x) (denom y))))
+  (define (sub-rat x y)
+    (make-rat (- (* (numer x) (denom y))
+                 (* (numer y) (denom x)))
+              (* (denom x) (denom y))))
+  (define (mul-rat x y)
+    (make-rat (* (numer x) (numer y))
+              (* (denom x) (denom y))))
+  (define (div-rat x y)
+    (make-rat (* (numer x) (denom y))
+              (* (denom x) (numer y))))
+  ;; interface to rest of the system
+  (define (tag x) (attach-tag 'rational x))
+  (put 'add '(rational rational)
+       (lambda (x y) (tag (add-rat x y))))
+  (put 'sub '(rational rational)
+       (lambda (x y) (tag (sub-rat x y))))
+  (put 'mul '(rational rational)
+       (lambda (x y) (tag (mul-rat x y))))
+  (put 'div '(rational rational)
+       (lambda (x y) (tag (div-rat x y))))
+  (put 'make 'rational
+       (lambda (n d) (tag (make-rat n d))))
+  'done)
+(define (make-rational n d)
+  ((get 'make 'rational) n d))