Question

It seems to happen all the time. For example:

(apply * (range 1 101))

gives me the error

ArithmeticException integer overflow  clojure.lang.Numbers.throwIntOverflow (Numbers.java:1374)

While in Ruby 1.9.2 the (conceptually) equivalent code,

(1..100).reduce(:*)

produces the desired result of

93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000

Obviously the two languages are quite different under the hood but it seems like they should both be able to handle this calculation without issue. Am I doing something wrong here? Or do I have an incorrect understanding?

Answer 1

You need to use some form of BigInteger.

Try (apply *' (range 1 101)).

(see http://dev.clojure.org/display/doc/Documentation+for+1.3+Numerics — evidently this auto-promotes upon overflow?)