Partial application of type constructors?

GHC 6.4 objects to the following simple program, pointing to the partial application of the type constructor AddL. Is there a work-around? {-# OPTIONS -fglasgow-exts #-} data LMap a b type AddL arr a b = a `arr` LMap a b data DFunA arr a b = DFunA (a `arr` b) (DFunA (AddL arr) a b) The complete error message: Type synonym `AddL' should have 3 arguments, but has been given 1 When checking the data constructor: forall arr a b. DFunA (arr a b) (DFunA (AddL arr) a b) In the data type declaration for `DFunA' Is there a serious difficulty with handling partial type applications? - Conal