This page is part of the web mail archives of SRFI 113 from before July 7th, 2015. The new archives for SRFI 113 contain all messages, not just those from before July 7th, 2015.
Kevin Wortman scripsit: > How about something like this (untested pseudocode) for alist->bag!: > > (define (alist->bag! bag alist) > (bag-delete-all! bag (map car alist)) Bag-delete-all doesn't remove all instances of the objects in the list, only one instance: it means "all in list", not "all copies". Maybe the name should be changed? And by the same token, maybe there should be bag operations to delete all copies of some object(s)? > (for-each (lambda (pair) > (unless (bag-contains? bag (car pair)) > (bag-increment! bag (car pair) (cdr pair)))) > alist)) That's what I said it should do, but on reflection it's not quite right. If the bag is {a, a, a} and the a-list says ((a . 1) (a . 2)), I think we should end up with {a, a, a, a} as a result of the (a . 1), and the (a . 2) should be ignored. Maybe this means that alist->bag! doesn't really make sense. Thoughts? -- John Cowan http://www.ccil.org/~cowan cowan@xxxxxxxx Principles. You can't say A is made of B or vice versa. All mass is interaction. --Richard Feynman