Hi cafe,

     I have played quite a bit with the ConstraintKinds extension, pretty cool.

     But I found a problem which I thought would be made better, plz correct me if I am wrong

     

     take a contrived example,      

     class C B => B a where 

     here B :: * -> Constraint,  I think this definition is reasonable, since B does not appears in the 

     first position of the context.

   

     Previously, we require acyclic class declarations since we don't have ConstraintKinds extension

     but now since type class could be abstracted, I think the definition above should be ok.

      

     the ghc-manual cited the program below is valid

    op :: D b => a -> b -> b
  }