On Mon, Jan 21, 2013 at 01:17:17AM +0200, mip...@meta.ua wrote: > The program looks like this: > > --*********************** > factorial :: Int->Int > factorial n = product [1..n] > > main = do > print $ factorial 50 > --*********************** > > And that yields "0" (no errors). Is it a bug or feature? :)
Int is fixed-size (*) and is expected to use modular arithmetics (**) therefore there is no notion of overflow, it just computes modulo maxBound::Int You must have been using a 32-bit haskell, that uses full-word Int, such as HUGS, and it turns out that using 32-bit signed integers, you eventually get -2**31 (this happens for n==32) and then multiplying by any even integer yields 0 (34!==0). GHC uses 31-bit or 63-bit Int (on 32- or 64-bit arch) and does not encounter this case before factorial 50 (however the answer is also not what you may have been expecting because it still doesn't fit). cheers *: this is specified in the standard **: this does not seem to be specified in the standard -- Benoit Triquet <benoit.triquet at gmail.com> .''`. : :' : We are debian.org. Lower your prices, surrender your code. `. `' We will add your hardware and software distinctiveness to `- our own. Resistance is futile. _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
