To the best of my knowledge the only guarantee you get is the *existence* of an upper bound on the size of the eagerly fetched chunk, so a potentially infinite lazy sequence will not result in an endless loop/OOME. The whole mechanism is based on a best-effort policy.
On Friday, March 15, 2013 2:08:58 AM UTC+1, Paul Butcher wrote: > > Clojure's sequences are lazy - but is there anything that guarantees *how* > lazy they are? > > To give a concrete example - given an infinite lazy sequence of promises: > > (def promises (repeatedly promise)) > > If, in one thread I do: > > (doseq [p (map deref promises)] (println p)) > > And in another thread, I call deliver on various elements of promises, > will promises always be printed as soon as they're available? Or can things > block for longer than they theoretically might because a later > (undelivered) promise in the sequence is being realized? > > I've been doing some experiments, and in practice the above works just > fine - promises are printed as soon as they theoretically might be. If, > however, I put a "flatten" in place of the map then I seem to have to > deliver one more promise before the first is printed. > > What I'm interested in here aren't practicalities. I'm interested in what > Clojure and its libraries guarantee (if anything) about laziness. Is there > an upper bound on how much of a sequence will be realized? > -- -- 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.
