I'm new to Haskell, as you can probably tell... I have the following data types: data Real a => Energy a = Energy a deriving (Eq, Ord, Show) data Real a => HeatC a = HeatC a deriving (Eq, Ord, Show) data Object h c = Object {energy :: (Energy h), heatc :: (HeatC c)} deriving (Eq, Show) data Real a => Temp a = Temp a deriving (Eq, Ord, Show) I'd like to make a function to calculate the temperature of an object. Physically this is the total heat times the heat capacity. I tried this with the following: temp :: (Real a) => Object (Energy a) (HeatC a) -> Temp a temp Object (Energy e) (HeatC c) = Temp e*c But this fails in hugs with: ERROR "temp.hs":22 - Constructor "Object" must have exactly 2 arguments in pattern What's the syntax to use here? Should I do this in some other way? Should I use newtype here instead of data?