In addition, as of 1.7, (range 1000) no longer creates a lazy sequence. It creates something that acts a bit like a sequence, but is reducable. So doing something like (reduce + 0 (range 1000)) is super fast and creates almost no garbage at all.
On Tue, May 10, 2016 at 5:46 PM, Alan Thompson <clooj...@gmail.com> wrote: > I don't understand what you mean. '(range 1000)' produces a lazy sequence, > and '(reduce + ...)' doesn't hold onto the head of the lazy sequence. > Therefore, each element can be GC'd as soon as added into the running > total, the the lazy sequence only produces new elements as they are > requested by the reduction (chunking aside, of course). > Alan > > On Tue, May 10, 2016 at 4:14 PM, JvJ <kfjwhee...@gmail.com> wrote: > >> That brings me to another thing I've wondered about. It is a typical >> clojure idiom to do something like (reduce + (range 1000)). >> >> But, unlike imperative loops, this will cache all those 1000 elements. >> This can kind of bloat memory, especially with large sequences? >> >> How can you get around it (other than tail-recursion or the while >> construction)? >> >> On Tuesday, 10 May 2016 09:45:50 UTC-7, Alex Miller wrote: >>> >>> Because some of the time you don't want caching. For example, if you >>> want to (later) reduce over a large (larger than memory even) external >>> resource. eductions allow you to define the source in one spot but defer >>> the (eager) reduction until later. >>> >>> On Tuesday, May 10, 2016 at 11:22:24 AM UTC-5, JvJ wrote: >>>> >>>> In that case, why aren't eductions just lazy sequences? >>>> >>>> On Monday, 9 May 2016 16:07:55 UTC-7, Alex Miller wrote: >>>>> >>>>> eductions are non-caching (will re-perform their work each time they >>>>> are used), so most of the time I would say lazy sequences are preferable. >>>>> >>>>> On Monday, May 9, 2016 at 4:54:48 PM UTC-5, JvJ wrote: >>>>>> >>>>>> In a similar vein, do you think that eductions are generally a better >>>>>> idea than lazy sequences/for comprehensions? >>>>>> >>>>>>> >>>>>>> -- >> 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. >> > > -- > 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. > -- “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/d/optout.
