[Haskell-cafe] New Eq instance

Hello, I had defined the follwing data type: data Step = Step Id Scenario Action State Response How can I define Step as an "Eq Instance", in such way that two steps are equals if they have the same Id (Id is defined as a synonimous for the String type). I tried the following code, but something is wrong.... instance Eq Step where Step id1 scenario1 action1 state1 response1 == Step id2 scenario2 action2 state2 response2 = id == id _ == _ = False ps.: sorry, this kind of basic question can be sent to this list? Thanks in advance. Rodrigo.