On 22.01.2009, at 16:27, Rich Hickey wrote: >> Now it works - fine. But what happened to the seq that now owns the >> stream? Nothing refers to it, so it should be gone. > > No, the stream must refer to it, in order to keep its promise to > return the same seq every time.
OK. >> Did it perhaps >> liberate the stream, so that I can create an iter again? Let's try: >> >> (def rand-iter (stream-iter rand-stream)) >> (next! rand-iter nil) >> (next! rand-iter nil) > What you've created an iter on the second time is the seq of the > stream. Right now, once you've treated a stream as a seq it will > always behave like one. So this second stream-iter call actually > creates an iter on a stream on that seq. Does that mean that calling seq on a stream converts the stream into a seq for all practical purposes? That sounds a bit dangerous considering that so many operations in Clojure call seq implicitly. One can easily have a seq "steal" a stream and not notice it before all memory is used up by the seq. > I understand this may not be intuitive or clear yet from the docs. Nor > am I set in this being the behavior. The case I am looking towards is > this one: > > (def s (stream (range 10))) > (if (seq s) > (take 4 (map-stream inc s)) > > A stream is used as a seq and then passed to a stream function. > Without this seqed-stream-behaves-as-seq capability, this will fail > with Already iterating, and would have to be written: > > (if (seq s) > (take 4 (map-stream inc (seq s)))) I think the second is in fact clearer. It seems weird in a largely functional context to have an enormous side-effect of calling seq on a stream. Konrad. --~--~---------~--~----~------------~-------~--~----~ 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 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 -~----------~----~----~----~------~----~------~--~---
