Just pay attention that when using later elements you don't need the earlier elements, and you should be fine. (IIRC)
2012/8/1 Vinay D.E <devi...@gmail.com>: > Thanks Sean & Carlo for the detailed comments! > The gap in my understanding was exactly *how* lazy 'lazy evaluation' is, so > the evaluation of 'i' is deferred until it is totally unavoidable. > > Just curious, but if I chained a large number of such lazy constructs, isn't > there danger of a big unpredictable spike in CPU / Memory if something > deeply nested is accessed ? > Is there someplace where this is discussed in detail, pros / cons, caveats, > concepts etc ? Any books that you think I should read ? > > Regards > Vinay > > > > On Tuesday, 31 July 2012 12:05:13 UTC+5:30, Sean Corfield wrote: >> >> > I tried putting a print and it works as expected. >> >> Because you are realizing the whole of i to print it. >> >> > 1) I assumed that printing out [i @a] instead of [@a i] should realize >> > 'i' >> >> No, [i @a] creates a two-element vector of a lazy-seq and a value (the >> deref of a). Then, when the REPL prints that vector, it realizes the >> lazy-seq. >> >> > 2) If I put a breakpoint in the predicate for take-while, it gets hit ( >> > I >> >> Yes, it is hit while i is being realized. >> >> > 3) This is the strangest observation of all: In the debugger I can see >> > that >> > 'a' is getting incremented, its changing when the breakpoint is hit! >> > but >> > the baffling thing is, when the result is printed out, I still get 0 as >> > the >> > value for a. >> >> Because the value of @a is bound before i is realized, so 0 is bound >> into the vector, and then i is realized during which process you see a >> being incremented. >> >> > Isn't (print i) the same as [i @a] ? since i is realized first, >> > shouldn't >> > @a be correctly printed? >> >> No, see above. >> >> > Why is the breakpoint showing me that a is changing ? >> >> Because it _is_ changing but _after_ the top level of the vector has >> been evaluated. >> -- >> Sean A Corfield -- (904) 302-SEAN >> An Architect's View -- http://corfield.org/ >> World Singles, LLC. -- http://worldsingles.com/ >> >> "Perfection is the enemy of the good." >> -- Gustave Flaubert, French realist novelist (1821-1880) > > -- > 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 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
