-- Recursive newtypes
| Just (rep_ty, co) <- splitNewTypeRepCo_maybe result_ty
= resultWrapper rep_ty `thenDs` \ (maybe_ty, wrapper) ->
-- Recursive newtypes
| Just (rep_ty, co) <- splitNewTypeRepCo_maybe result_ty
= resultWrapper rep_ty `thenDs` \ (maybe_ty, wrapper) ->