Haskell / Free Monad / How can I do something like this?

freedsl.hs

data A = A Text
data B = B Text A

data ActionC t next = InsertC t (t -> next)
instance Functor (ActionC t) where
  fmap f (InsertC a b)= InsertC a (f . b)

insertC a = liftF (InsertC a id)

proC txt1 txt2 = do
  a <- insertC $ A txt1
  b <- insertC $ B txt2 a
  return b

I think you want 'String' in place of 'Text' in your definitions of A and B.
Not in scope: type constructor or class `Text'
Don't know if it does what you want, but it compiles when I make that change.