如何为教堂编码的自由monad编写拆封程序？(Haskell)

import Control.Monad.Free
import Control.Monad.Trans.Free

data ChurchCodeF a = -- 自定义自由monad的构造器
    -- 在这里定义自由monad的操作，例如：
    Pray String a
    | Sing String a
    | ...

instance Functor ChurchCodeF where
    fmap f (Pray str next) = Pray str (f next)
    fmap f (Sing str next) = Sing str (f next)
    ...

type ChurchCode = Free ChurchCodeF

pray :: String -> ChurchCode ()
pray str = liftF (Pray str ())

sing :: String -> ChurchCode ()
sing str = liftF (Sing str ())

-- 其他自定义操作函数...

interpret :: ChurchCodeF a -> IO a
interpret (Pray str next) = do
    putStrLn ("Praying: " ++ str)
    pure next

interpret (Sing str next) = do
    putStrLn ("Singing: " ++ str)
    pure next

-- 其他自定义操作的解释函数...

runChurchCode :: ChurchCode a -> IO a
runChurchCode = foldFree interpret