On Wed, Aug 24, 2011 at 3:49 PM, Asim Jalis <asimja...@gmail.com> wrote: > I used "take 0" as a simple example to illustrate the problem. But in general > the standard mapcat evaluates terms than are needed. My f function does a web > call and processes the JSON records produced by this call, so each extra call > is a significant performance and resource hit.
You may be able to wrap each web call in an explicit delay, and construct your lazy seq of these delays, then force the ones you actually want to use. Then the expensive JSON calls won't take place for any element until needed, no matter how far any of the sequence processing functions look ahead, as long as none of them will need to peek inside the delays until outside the problematic mapcat. (So, (mapcat (filter ...)) would be trouble, as the filter predicate may need to force the delays in the inner sequence, but (filter (mapcat ...)) should be ok unless filter is also looking ahead.) -- Protege: What is this seething mass of parentheses?! Master: Your father's Lisp REPL. This is the language of a true hacker. Not as clumsy or random as C++; a language for a more civilized age. -- 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
