Hi Randy, Several functions in clojure.set allow non-set arguments and this has been an issue with a long history. There have been or are tickets like this, such as http://dev.clojure.org/jira/browse/CLJ-1682 (although this one is re intersection).
This was done somewhat intentionally for performance reasons - rather than validate or transform, just assume they are sets - their behavior when passed non-sets is considered undefined. However, I think this is worth revisiting in light of where we are today vs then. I do not know of a jira specific to clojure.set/union - you are welcome to create one via the contribution process documented at http://clojure.org/community/contributing. Alex On Friday, March 4, 2016 at 11:40:28 AM UTC-5, Randy J. Ray wrote: > > Hi, > > Fairly-new Clojure enthusiast here, currently using Clojure to work > through projecteuler.net problems as a means of learning. While using > sets on one of the PE problems, I encountered what *might* be a bug. I > admit that I haven't searched the backlog of messages from this group or > the issues on GitHub, so if this is already known I apologize. > > Here is the issue: I discovered that I could pass a list as the second > parameter to set/union, and it would be merged into the the set passed as > the first parameter and the new resulting set returned. However, if the > number of items in the list exceeds the number of items in the set, then > the return value is a list with any duplicate elements completely present. > > To illustrate, here is a snippet from my REPL: > > user=> (require '[clojure.set :as set]) > nil > user=> (set/union #{1 2 3} #{2 3 4}) > #{1 4 3 2} > user=> (set/union #{1 2 3} #{2 3 4 5}) > #{1 4 3 2 5} > user=> (set/union #{1 2 3} (list 2 3 4)) > #{1 4 3 2} > user=> (set/union #{1 2 3} (list 2 3 4 5)) > (2 3 1 2 3 4 5) > > Note that the last expression yields a list of 7 elements rather than a > set of 5. > > I have not tried this with more than two arguments, so I don't know that > would affect the output. I did try putting a list as the first parameter, > and that results in a list return value all the time. > > Is this a bug? Should I file a GitHub issue on this? I first encountered > this in 1.7.0, but I recently updated to 1.8.0 and it is still present. > > Randy > -- > Randy J. Ray - randy.j....@gmail.com - twitter.com/rjray > Silicon Valley Scale Modelers: http://www.svsm.org > Sunnyvale, CA > -- 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/d/optout.
