classes and instances

Hello, I'm learning haskell and I'm having some trouble with type classes. I understand them conceptually, but when I try to create an instance I run into problems. As a simple example, I create a class called ToInt:

class ToCh a where int :: a -> Int

Then I create an instance:

instance ToInt Int where: int n = n

However, when I try to use the function int :: Int -> Int at the hugs prompt, I get the following error message: Main> int 5 ERROR - Unresolved overloading *** Type : (Num a, ToInt a) => Int *** Expression : int 5 Can someone explain what the problem is, and how to interpret the error message I'm getting? thanks _t