But that would print 1 to 32 items depending on a ton of things. No the correct way to write code like that is
(doseq [s coll] (println s)) If you need to iterate over multiple items then use (map f a b). Also I would suggest benchmarking things, sure (map f coll) is slower than a transducer, but benchmark your app code and I think you'll be surprised how fast map is for normal use cases. On Fri, Sep 23, 2016 at 4:04 PM, William la Forge <laforg...@gmail.com> wrote: > I've run into this when I wanted to print each item in a seq. Since > println returns nil, I just did (first (keep println coll)). --Needed the > first here because keep returns a lazy seq. > > > On Friday, September 23, 2016 at 12:02:09 AM UTC-4, Mars0i wrote: >> >> This is almost the same as an issue I raised in this group over a year >> and a half ago, here >> <https://groups.google.com/forum/#!msg/clojure/bn5QmxQF7vI/vO1XLSyPXC8J;context-place=forum/clojure>. >> I suggested that Clojure should include function with map's syntax but that >> was executed only for side-effects, without constructing sequences. No one >> else was interested--no problem. It's still bugging me. >> >> It's not map syntax that I care about at this point. What's bugging me >> is that there's no standard, built-in way to process multiple sequences for >> side effects without (a) constructing unnecessary sequences or (b) rolling >> my own function with loop/recur or something else. >> >> If I want to process multiple sequences for side-effects in the the way >> that 'for' does, Clojure gives me 'doseq'. Beautiful. I can operate on >> the cross product of the sequences, or filter them in various ways. >> >> If I want to process multiple sequences by applying an n-ary function to >> the first element of each of n sequences, then to the second element of >> each sequence, and so on, I can use 'map' or 'mapv', but that means >> constructing unnecessary collections. >> >> Or I can splice my n sequences together, and make a single sequence of >> n-tuples, and use doseq to process it. (There's an example like this on >> the doseq doc page.) Or I can process such a sequence with 'reduce'. More >> unnecessary collections, though. >> >> Or I can use 'dotimes', and index into each of the collections, which is >> OK if they're vectors, but ... ugh. why? >> >> Or I can construct my own function using first and rest or first and next >> on each of my sequences, via loop/recur, for example. But that seems odd >> to me. >> >> Isn't this a common use case? Is processing multiple sequences for >> side-effects with corresponding elements in each application so unusual? >> (Am I the only one?) Isn't it odd that we have doseq and map but nothing >> that processes multiple sequences for side-effects, in sequence, rather >> than as a cross-product? >> >> (I admit that in my current use case, the sequences are small, so >> creating a sequence of n-tuples would have only a trivial cost. It just >> bugs me, though. :-) >> >> I'd still be OK with something that had a map-like syntax, but my current >> inclination is that it would be better for such a function to have >> doseq-style syntax. The name might be derived from "doseq"--maybe >> "doseq*". >> >> (I'd be willing to suggest this in a JIRA ticket, but that doesn't seem >> reasonable unless there's a call for something like this from more than one >> person.) >> > -- > 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. > -- “One of the main causes of the fall of the Roman Empire was that–lacking zero–they had no way to indicate successful termination of their C programs.” (Robert Firth) -- 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.
