I can't answer whether Clojure should do that. It is doing it because unchecked-multiply falls back to normal multiply, i.e. *, unless both of its arguments are primitive long values. Even boxed Long values cause it to fall back to the behavior of *. The same goes for unchecked-add and unchecked-subtract.
user=> (unchecked-multiply 2432902008176640000 21) -4249290049419214848 user=> (unchecked-multiply 2432902008176640000 (Long. 21)) ArithmeticException integer overflow clojure.lang.Numbers.throwIntOverflow (Numbers.java:1501) Andy On Fri, Oct 23, 2015 at 1:54 PM, Garrett Rowe <gmrowe1...@gmail.com> wrote: > Should `unchecked-multiply` throw an exception in this case? (see also: > http://stackoverflow.com/questions/33306984/why-does-my-hash-function-fail-with-arithmeticexception-integer-overflow-even/33308956#33308956 > ) > > user> (reduce unchecked-multiply (range 1 22)) > ArithmeticException integer overflow clojure.lang.Numbers.throwIntOverflow > (Numbers.java:1388) > > The loop-recur version also fails, unless you use a type hint: > > user> (loop [n 1 > r (range 1 22)] > (if-let [a (first r)] > (recur (unchecked-multiply n a) (next r)) > n)) > ArithmeticException integer overflow clojure.lang.Numbers.throwIntOverflow > (Numbers.java:1388) > > user> (loop [n 1 > r (range 1 22)] > (if-let [^long a (first r)] > (recur (unchecked-multiply n a) (next r)) > n)) > -4249290049419214848 > > -- > 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. > -- 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.
