On 13 May 2013 17:30, Timothy Baldridge <tbaldri...@gmail.com> wrote: >>> In fact, the way that count works on ISeqs is rather roundabout -- it > only works because all implementations of ISeq in clojure.jar also > happen to implement java.util.List, so count calls Collection.size(). > In theory, some user-provided ISeq which didn't implement List would > not respond to count. > > ------ > > That is just completely untrue: > > https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/RT.java#L536 > https://github.com/clojure/clojure/blob/master/src/clj/clojure/core.clj#L826
Thanks for the correction. I had read this code before and I read it again and couldn't see any mistake, until I looked at ISeq and realized it implements IPersistentCollection. That came as a surprise to me. I guess I'm used to treating seqs and colls as very separate ideas that I simply didn't expect that ISeq would implement IPersistentCollection. Phil > Timothy > > > > On Mon, May 13, 2013 at 10:17 AM, Philip Potter <philip.g.pot...@gmail.com> > wrote: >> >> In fact, the way that count works on ISeqs is rather roundabout -- it >> only works because all implementations of ISeq in clojure.jar also >> happen to implement java.util.List, so count calls Collection.size(). >> In theory, some user-provided ISeq which didn't implement List would >> not respond to count. >> >> It's probably a good idea for interop reasons to have seqs implement >> the java collection types, but I don't feel too happy about clojure >> code which uses the java Collection interface on seqs. >> >> Phil >> >> On 13 May 2013 15:48, Meikel Brandmeyer (kotarak) <m...@kotka.de> wrote: >> > Hi, >> > >> > Am Montag, 13. Mai 2013 16:16:57 UTC+2 schrieb Sean Corfield: >> >> >> >> >> >> So you think (count (map inc [1 2 3])) should be illegal? >> >> >> >> (I'm just trying to understand your logic here) >> >> >> > >> > In the hardcore version, yes. In the practical version, probably not. I >> > never had to call count on a seq. (Various versions of partition-by or >> > split >> > being a notable exception.) (Still a promised O(1) count would be nice >> > for >> > reasoning as we have it for contains?. What is clojure.lang.Counted good >> > for >> > anyway?) >> > >> > Meikel >> > >> > -- >> > -- >> > 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. >> > >> > >> >> -- >> -- >> 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. >> >> > > > > -- > “One of the main causes of the fall of the Roman Empire was that–lacking > zero–they had no way to indicate successful termination of their C > programs.” > (Robert Firth) > > -- > -- > 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. > > -- -- 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.
