callCC oddness

for some reason

fac n = (`runCont` id) $
          callCC $ \k -> do
            when (n == 1) $ k 1
            return $ n * fac (n - 1)

is faster and uses less memory (for n=10000) than

fac' = product . enumFromTo 1

or [code]fac'' n = foldr1 (*) [1..n]

what gives /prog/?

Bitches don't know about my http://www.haskell.org/haskellwiki/Stack_overflow