On Wed, Jul 15, 2009 at 9:58 AM, Mark Engelberg<mark.engelb...@gmail.com> wrote: > The problem with subvec is that it doesn't really create a "new" > vector, it just adds a level of indirection off of the original > vector. So for example, if you look up, say, index 2 in the subvec, > it knows to go look up index 5 in the original vec. If you create a > subvec of a subvec of a subvec, etc. pretty soon every lookup results > in a chain of forty lookups until it gets to the original vector, and > your performance grinds to a halt.
I take this back. I realized that I was repeating an assertion I have heard on this list, without confirming it for myself. Looking at the code for subvector, it looks like it indeed does the intelligent thing and a subvec of a subvec points directly at the new start and end bounds for the original vector. So there really shouldn't be a performance penalty for nested subvecs. So your use of subvec in stack-dropn is fine. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
