From: ri...@happyleptic.org > > What you're asking is similar to the problem of finding the predecessor > > of an arbitrary node in a singly-linked-list. You have no option but to > > scan the whole list to find its predecessor. If you had a > > doubly-linked-list, predecessor lookups would work easily, but that's a > > different data structure, with much more overhead. > > Much more overhead, really ? > So this is for performance reasons that all functionnal languages > promote singly-linked lists, while for instance in Linux every list > is implemented with a doubly linked list for purely ideological reasons ? > > :-)
Yes indeed, much more overhead. But the source is not the fact you have to maintain backlinks, but their impact on the GC. With a GC, any modification on existing values has a cost, since you have to keep track of them independently of the value itself. Since linux has no GC, using doubly linked lists has only a very limited cost, mostly related to the extra space needed. By the way, BSD uses lots of singly-linked lists, probably because it comes from a time when there was not so much memory. Jacques Garrigue _______________________________________________ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
