memo

(define *alist* '())


(define (union set1 set2)
 (cond ((null? set1) set2)
  ((member (car set1) set2) (union (cdr set1) set2))
  (else (cons (car set1) (union (cdr set1) set2)))))


(define (union-alist! lst)
 (let ((l (assoc (car lst) *alist*)))
  (set! (cdr l) (list (union (cadr l) (cadr lst))))))


(define (add-alist! lst)
 (push! *alist* lst))


(define (add-or-union-alist! lst)
 (if (assoc (car lst) *alist*)
  (union-alist! lst)
  (add-alist! lst)))

(for-each (lambda (lst) (add-or-union-alist! lst)) '((a (s d f)) (b (q w e)) (a (y u i s s))))


*alist*
((b (q w e)) (a (d f y u i s s)))

#Gauche #Scheme #Lisp

SN 2013/07/03 15:20:28

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