can't declare instance for type synonim

Trying to load into GHCi simple program (in attached 
file) I receive error stating I can declare class instances 
only for types defined using "data". I beleive it is a bug 
because Hugs handles this situation normally.
Error message:
/igor/tst.hs:1:
    No instance for `Eq (Stack -> Stack)'
    When deriving the `Eq' instance for type `Object'

/igor/tst.hs:1:
    No instance for `Show (Stack -> Stack)'
    When deriving the `Show' instance for type `Object'

/igor/tst.hs:4:
    Illegal instance declaration for `Eq Operator'
        (The instance type must be of form (T a b c)
         where T is not a synonym, and a,b,c are distinct 
type variables)
    In the instance declaration for `Eq Operator'

/igor/tst.hs:6:
    Illegal instance declaration for `Show Operator'
        (The instance type must be of form (T a b c)
         where T is not a synonym, and a,b,c are distinct 
type variables)
    In the instance declaration for `Show Operator'

Trac metadata

Trac field	Value
Version	None
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	ResolvedRejected
Component	Compiler (Type checker)
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