+; Type dispatch and promotion
+
+(define (type-dispatch ops x)
+ (if (flonum? x)
+ ((cdr ops) x)
+ ((car ops) x)))
+
+(define (promote-dispatch ops x y)
+ (if (flonum? x)
+ (if (flonum? y)
+ ((cdr ops) x y)
+ ((cdr ops) x (fixnum->flonum y)))
+ (if (flonum? y)
+ ((cdr ops) (fixnum->flonum x) y)
+ ((car ops) x y))))
+