[Haskell-beginners] How to avoid repeating a type restriction from a data constructor

In http://code.accursoft.com/binding/src/c13ccbbec0ba8e326369ff2252863f20a891ef... there's a data constructor data Source v a = Variable v => Source {bindings :: v [Binding a], var :: v a} Source is used many times in this file and in http://code.accursoft.com/binding/src/c13ccbbec0ba8e326369ff2252863f20a891ef..., and each time, I have to repeat the context Variable v. Is there any way to avoid this redundancy?