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 get the error:
Couldn't match type A' withB'
When using functional dependencies to combine
MonadFree (ActionC A) m0,
arising from a use of insertC' at Transact.hs:96:8-14 MonadFree (ActionC B) m0, arising from a use ofinsertC' at Transact.hs:97:8-14
In the expression: insertC
In a stmt of a 'do' block: b <- insertC $ B txt2 a

How can I fix this so that it compiles?

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.