Thanks - useful idioms to know about! On Friday, 18 July 2014 16:18:33 UTC+9:30, puzzler wrote: > > Yeah, you've answered your own question. In practice, I doubt the > difference is measurable. > > Another common idiom you see in Clojure code is: > (defn f [xs] > (if-let [s (seq xs)] > ...do something with (first s) and (f (rest s))... > ...base case...)) > > This ensures that you seq-ify the input (rather than assuming it has been > seq'ed before passed in), gives you the fast test against nil, and uses > rest rather than next because next would have the effect of causing an > extra unnecessary call to seq. > > In a loop-recur situation, it is more common to do the seq once in the > initialization of the loop and then use next which calls seq: > > (defn f [xs] > (loop [s (seq xs)] > (if s > ... (recur (next s))... > ... base case ...))) > > > Out of habit, I prefer to see the base case first so I don't usually do > either of these, but these two patterns are a very popular style, and very > fast execution. If you don't have a pre-existing preference, these would > be good choices. >
-- 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.
