1 (define (apply-generic op . args)
2   (define (try-convert x new-type)
3     (let ((converter (get-coercion (type-tag x) new-type)))
4       (if converter
5 	  (converter x)
6 	  x)))
7   (define (apply-generic-1 op args type-list)
8     (if (null? type-list)
9 	(error "No method for these types"
10 	       (list op (map type-tag args)))
11 	(let ((new-args (map (lambda (x)
12 			       (try-convert x (car type-list)))
13 			     args)))
14 	  (let ((new-type-tags (map type-tag new-args)))
15 	    (let ((proc (get op new-type-tags)))
16 	      (if proc
17 		  (apply proc (map contents new-args))
18 		  (apply-generic-1 op args (cdr type-list))))))))
19   (let ((type-tags (map type-tag args)))
20     (let ((proc (get op type-tags)))
21       (if proc
22 	  (apply proc (map contents args))
23 	  (apply-generic-1 op args type-tags)))))