if you do it as a lock, then readers must block writers (think it through). Clojure's reference types + immutable datastructures and the views on perception that underlay them are strongly opposed to readers interfering with writers.
http://www.infoq.com/presentations/Are-We-There-Yet-Rich-Hickey around 27:48 Rich discusses perception On Tue, Jul 17, 2012 at 3:57 PM, Warren Lynn <wrn.l...@gmail.com> wrote: > I have a hard time understanding why there is a need to retry when doing > "swap!" on an atom. Why does not Clojure just lock the atom up-front and do > the update? I have this question because I don't see any benefit of the > current "just try and then re-try if needed" (STM?) approach for atom (maybe > OK for refs because you cannot attach a lock to unknown ref combinations in > a "dosync" clause). Right now I have an atom in my program and there are two > "swap!" functions on it. One may take a (relatively) long time, and the > other is short. I don't want the long "swap!" function to retry just because > in the last minute the short one sneaked in and changed the atom value. I > can do the up-front lock myself, but I wonder why this is not already so in > the language. Thank you for any enlightenment. > > -- > 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 -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- 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
