test.scm

(define (make-rat n d)
  (cond ((and (< n  0) (< d  0)) (cons (- n ) (- d)))
        ((< d 0) (cons (if (< n 0) (+ n) n) d))
        ((and (> n 0) (> d 0)) (cons n d))))

(define (numer x)
  (car x))

(define (denom x)
  (cdr x))

;(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)) (* (numer y) (denom x))))



(define (print-rat x)
  (newline)
  (display (numer x))
  (display "/")
  (display (denom x)))

(define  testing (make-rat (- 1) (- 2)))
(print-rat testing)

(define  testing (make-rat 1 (- 2)))
(print-rat testing)

;(define test (make-rat 1 3))
;(print-rat test)

;(print-rat ( add-rat testing test))