-- (ppr_extra env ty) shows extra info about 'ty'
ppr_extra :: TidyEnv -> Type -> TcM (TidyEnv, SDoc)
ppr_extra env (TyVarTy tv)
-- (ppr_extra env ty) shows extra info about 'ty'
ppr_extra :: TidyEnv -> Type -> TcM (TidyEnv, SDoc)
ppr_extra env (TyVarTy tv)