A tiny, not so important, thing in the solution of Homework 06

[Tony-Makdissy]

In lines 98 & 104 of 6th lesson solution, namely

factorial :: Int -> String

and

    result = product [1 .. n]

I think the type should be Integer instead of Int, it seems the same but this code won't work if n > 20. I know this homework isn't meant to deal with such things, but I think it's a good opportunity to show when Integer is more suitable than Int.