Way back when I started with Clojure i was doing this: (let [constant-data (something-expensive)] (defn my-fn [x] (do-something-with x constant-data)))
But was advised instead to do this: (def my-fn (let [constant-data (something-expensive)] (fn [x] (do-something-with x constant-data)))) So, there's that (third) option as well. // ben On Sat, Mar 23, 2013 at 9:56 AM, Marko Topolnik <marko.topol...@gmail.com>wrote: > What if there's some computation in there, but such that should be > performed at compile time? I still prefer the outside let whenever I want > to make dead sure it's not getting reallocated on each call. If there was > some well-specified and easily understood guarantee (for example, like the > one Java has for compile-time constants), only then I would prefer the > inner let. > > > On Friday, March 22, 2013 8:05:10 PM UTC+1, Laurent PETIT wrote: > >> >> 2013/3/22 jamieorc <jami...@gmail.com> >> >>> Curious which style is preferred in Clojure and why: >>> >>> (defn f1 [] >>> (let [x {:foo 1 :bar 2 :baz 3}] >>> (keys x))) >>> >>> (let [x {:foo 1 :bar 2 :baz 3}] >>> (defn f2 [] >>> (keys x))) >>> >> >> In either case, AFAIK, the compiler will recognize {:foo 1 :bar 2 :baz 3} >> as constant and will only create it once when compiling. >> >> First version is preferred. >> >> >>> >>> Cheers, >>> >>> Jamie >>> >>> -- >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Clojure" group. >>> To post to this group, send email to clo...@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+u...@**googlegroups.com >>> >>> For more options, visit this group at >>> http://groups.google.com/**group/clojure?hl=en<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+u...@**googlegroups.com. >>> >>> For more options, visit >>> https://groups.google.com/**groups/opt_out<https://groups.google.com/groups/opt_out> >>> . >>> >>> >>> >> >> -- > -- > 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/groups/opt_out. > > > -- -- 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/groups/opt_out.