I recently experimented with that kinda stuff. See the following:

type family SelectPrivilege a :: Bool
type instance SelectPrivilege ReadTransaction  = True
type instance SelectPrivilege WriteTransaction = True

type family UpdatePrivilege a :: Bool
type instance UpdatePrivilege ReadTransaction  = False
type instance UpdatePrivilege WriteTransaction = True

data Read
data Write

data Transaction t r

executeUpdateTransaction :: UpdatePrivilege t ~ True => Transaction t r -> IO r
executeUpdateTransaction =
  undefined
​

The above code ensures that transactions of type Transaction Read r cannot be executed using the executeUpdateTransaction function. However then the same type level logic can be encoded using an existence of a type class instance:

class SelectPrivilege t
instance SelectPrivilege ReadTransaction
instance SelectPrivilege WriteTransaction

class UpdatePrivilege t
instance UpdatePrivilege WriteTransaction

data Read
data Write

data Transaction t r

executeUpdateTransaction :: UpdatePrivilege t => Transaction t r -> IO r
executeUpdateTransaction =
  undefined