Compute Product of Values in Bag

[Sergey Goder <se...@gmail.com>]

I was wondering if there is a way to compute the product of all the values
in a bag much like the built in function SUM does currently.

For reference, I am currently implementing a multinomial naive bayes
classifier and need to compute the product of probabilities. I am trying to
avoid using a UDF because the requirements of the project prohibit me from
using a secondary language such as python, javascript, etc.

Thanks,
Sergey