Even though vectors aren't as prone to collision between similar-looking vectors, I think you are right that the smallness of the numbers is a problem:
Consider the following: => (count (set (for [x (range 200) y (range 200)] (hash [x y])))) 6369 This means that out of 40,000 common ordered pairs, there are only 6369 distinct hash values. That's not good. So yes, upon further thought, I think sequence hashing should be improved as well. I want to emphasize that I don't view this as merely a "theoretical" problem. I have noticed for over a year now, when profiling my Clojure code, that a surprising amount of time was spent on dealing with hash collisions. I chalked it up as the natural behavior of hash tables which will occasionally have collisions, and just learned to live with it, but the more I play around with the existing hash function on data similar to what I use (with small numbers in slightly varying structures), the more I'm convinced that Clojure's weak hashing strategy explains the performance issues I've had. Would love to see the Clojure community tackle this head-on; I think there's a lot of performance to be gained for many real apps by doing this. -- -- 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 --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
