On Sun, Aug 8, 2010 at 12:12 AM, Meikel Brandmeyer <m...@kotka.de> wrote: > Just for fun another low-level solution: > > (defn partition-when > [pred coll] > (let [step (fn [p s] > (if s > (let [fst (first s)] > (if (pred fst) > [p s] > (recur (conj p fst) (next s)))) > [p nil]))] > (lazy-seq > (when-let [s (seq coll)] > (let [[p r] (step [(first s)] (next s))] > (cons p (partition-when pred r))))))) > > Hopefully not holding onto the head, as lazy as it can get and working with > infinite input.
I wrote a similar version in F# which does have the advantage of handling infinite input or a very long partition in the sense that I can still consume the first element immediately and can skip to the second, third group ... In a sense, the result is a lazy list of lazy list and if the consumer doesn't hold on to any of them, the memory usage is constant. It is slower than a non-lazy version in F# when the input is not too long in size. I don't know about the characteristic of the current partition-by in core, as this version would be a nice addition for its capability of handling long input effectively. -- 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
