If you do not insist on vanilla clojure, but can use a library, fold from fluokitten might enable you to do this. It is similar to reduce, but accepts multiple arguments. Give it a vararg folding function that prints what you need and ignores the first parameter, and you'd get what you asked for.
On Friday, September 23, 2016 at 7:15:42 PM UTC+2, Mars0i wrote: > > On Friday, September 23, 2016 at 11:11:07 AM UTC-5, Alan Thompson wrote: >> >> Huh. I was also unaware of the run! function. >> >> I suppose you could always write it like this: >> >> (def x (vec (range 3))) >> (def y (vec (reverse x))) >> >> (run! >> (fn [[x y]] (println x y)) >> >> (map vector x y)) >> >> >> > lein run >> 0 2 >> 1 1 >> 2 0 >> >> > Yes. But that's got the same problem. Doesn't matter with a toy example, > but the (map vector ...) could be undesirable with large collections in > performance-critical code. > > although the plain old for loop with dotimes looks simpler: >> >> (dotimes [i (count x) ] >> (println (x i) (y i))) >> >> >> maybe that is the best answer? It is hard to beat the flexibility of a a >> loop and an explicit index. >> > > I agree that this is clearer, but it kind of bothers me to index through a > vector sequentially in Clojure. We need indexing In Clojure because > sometimes you need to access a vector more arbitrarily. If you're just > walking the vector in order, we have better methods--as long as we don't > want to walk multiple vectors in the same order for side effects. > > However, the real drawback of the dotimes method is that it's not > efficient for the general case; it could be slow on lists, lazy sequences, > etc. (again, on non-toy examples). Many of the most convenient Clojure > functions return lazy sequences. Even the non-lazy sequences returned by > transducers aren't efficiently indexable, afaik. Of course you can always > throw any sequence into 'vec' and get out a vector, but that's an > unnecessary transformation if you just want to iterate through the > sequences element by element. > > If I'm writing a function that will plot points or that will write data to > a file, it shouldn't be a requirement for the sake of efficiency that the > data come in the form of vectors. I should be able to pass in the data in > whatever form is easiest. Right now, if I wanted efficiency for walking > through sequences in the same order, without creating unnecessary data > structures, I'd have to write the function using loop/recur. On the other > hand, if I wanted the cross product of the sequences, I'd use doseq and be > done a lot quicker with clearer code. > -- 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 unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
