Hi! This is happening because you have integers saved to a global variable.
(iterate inc 1) creates an infinite lazy seq. Def-fing it to a global says 'Hey, i might want this later!' to Clojure. This means that as you take numbers from integers; they get saved in memory rather than being garbage collected. This is why you run out of memory. You'll notice that this version: (limited-reduce + (iterate inc 1) 1000000) Runs (in a nice constant memory) even though yours (which almost appears equivalent) will not! In fact, even this version: (limited-reduce + (iterate inc 1) 1000000000) Runs in a nice constant space memory, although it takes a long time. Nothing is wrong with the code, its that darn data! If you are interested in this stuff, read about 'Haskell performance tips'. A lot of people would make references to 'holding on to the head' and such, and it would pretty much go 'whoooosh' right over /my/ head. Then I read a bit about how Haskell and how laziness there worked, and it started to make sense. Hope this helps, -Jon On Sep 18, 3:52 pm, Patrik Fredriksson <patri...@gmail.com> wrote: > Hi! > > Could someone please help me understand why the following causes a > java.lang.OutOfMemoryError: Java heap space for large n:s (100000 > works fine, 1000000 does not). > > (def integers (iterate inc 1)) > > (defn limited-reduce [fn coll n] > (loop [c coll i n result 0] > (if (zero? i) > result > (recur > (rest c) > (dec i) > (fn result (first c)))))) > > (limited-reduce + integers 100000) > > Many thanks! > > /Patrik --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
