Incremental hashcode calculation for collections

Question

Reported by richhickey, Dec 17, 2008 So hachCode can be final, more efficient to calc as you go. Formerly Google Code Issue 11

Answer 1

Comment made by: importer

Converted from http://www.assembla.com/spaces/clojure/tickets/15

Answer 2

Comment made by: cgrand

Wouldn't the naive approach incur realizing lazy sequences when adding them to a list or a vector or as values in a map?

Answer 3

Comment made by: cgrand

The lazy-incremental-hashes.diff introduces lazy incremental hashes based on structural sharing.

Answer 4

Comment made by: cgrand

Why is this identified as Blocker?

Answer 5

Comment made by: cgrand

setting priority to minor

Answer 6

Comment made by: jafingerhut

I've seen this "edit a ticket, it changes to Priority=Blocker" behavior before. I believe some of the older tickets have no Priority field at all, and when you edit any of their properties, it creates the priority field with a default value of Blocker.

Answer 7

Comment made by: alexmiller

Yes, concur with Andy's explanation on priority change. I just bulk-edited all open CLJ tickets with null priority and set their priority.

Answer 8

Comment made by: jafingerhut

Patch lazy-incremental-hashes.diff still applies cleanly as of Jan 30 2014 latest Clojure master, but now fails tests due to recent commits involving hash changes. I have not checked how difficult or easy it might be to update the patch to pass tests again.

Answer 9

Comment made by: jafingerhut

Patch lazy-incremental-hashes.diff dated Aug 26 2013 no longer applied cleanly to latest master after some commits were made to Clojure on Aug 29, 2014. It did apply cleanly before that day.

I have not checked how easy or difficult it might be to update this patch.

Answer 10

Comment made by: jafingerhut

Patch lazy-incremental-hashes.diff dated Aug 26 2013 applies cleanly again to latest Clojure master as of Sep 5 2014, even though the patch has not been updated. I haven't checked, but I would guess this is because one of the changes made to Clojure master recently was reverted with this commit: https://github.com/clojure/clojure/commit/46be47c9f51ef10d0082f1bd39ffff1008682861

Answer 11

Reference: https://clojure.atlassian.net/browse/CLJ-15 (reported by richhickey)