You can think a monad defines a DSL. Let's take for example the Rand[0] monad:

    type Rand g = RandT g Identity

    newtype RandT g m a = ...

    -- with
    runRandT :: (Monad m, RandomGen g) => RandT g m a -> g -> m (a, g)
    newtype MyType = Rand StdGen

    -- now you can define
    intGreaterThan :: Integer -> MyType Integer
    intGreaterThan = ...

    randomName :: Integer -> MyType String
    randomName length = ...

    -- an finally convine the two above

    nRandomNames :: Integer -> Integer -> MyType [String]
    nRandomNames length n
       | n <=0 = return []
       | otherwise = do
           tailNames <- nRandomNames (n-1)
           headName <- randomName length
           return (headName:tailNames)

These functions of type `...->MyType a` can be viewed as a DSL where the Random generator state is abstracted away.

[0]hackage.haskell.org/package/MonadRandom-0.3/docs/Control-Monad-Random.html