Hi, after some playing around with monad transformers and starting to like those specialities of Haskell, I am currently really feeling thrown back by a simple problem: trying to write a sine-function... Here is the part of my code that is troubling me: fac :: Integer -> Integer fac n = product [1..n] term :: Double -> Integer -> Double term x n = (-1.0::Double)**(fromInteger n) * (x**(fromInteger (2*n + 1))) / (fromInteger (fac (2*n + 1))) The term function is supposed to be the direct translation of the formula of a term within the sum. But it isn't: it is actually cluttered with lots of type conversions, and I had a hard time figuring out how to make it work at all. I hope that this is not the easiest way to do that and I would appreciate any help on how to handle those type conversion issues... Thanks, Chris