I think there's a typo in section 7.3.12.3: [[ You can't use existential quantification for newtype declarations. So this is illegal: newtype T = forall a. Ord a => MkT a Reason: a value of type T must be represented as a pair of a dictionary for Ord t and a value of type t. That contradicts the idea that newtype should have no concrete representation. You can get just the same efficiency and effect by using data instead of newtype. If there is no overloading involved, then there is more of a case for allowing an existentially-quantified newtype, because the data because the data version does carry an implementation cost, [--------------] [--------------] ... Repeated clause but single-field existentially quantified constructors aren't much use. So the simple restriction (no existential stuff on newtype) stands, unless there are convincing reasons to change it. ]] #g ------------ Graham Klyne GK@NineByNine.org