相关疑难解决方法(0)

我最近一直在教自己关于免费套餐中的Freemonad ,但我遇到了一个问题.我想为不同的库提供不同的免费monad,基本上我想为不同的上下文构建DSL,但我也希望能够将它们组合在一起.举个例子:

{-# LANGUAGE DeriveFunctor #-}
module TestingFree where

import Control.Monad.Free

data BellsF x
    = Ring x
    | Chime x
    deriving (Functor, Show)

type Bells = Free BellsF

data WhistlesF x
    = PeaWhistle x
    | SteamWhistle x
    deriving (Functor, Show)

type Whistles = Free WhistlesF

ring :: Bells ()
ring = liftF $ Ring ()

chime :: Bells ()
chime = liftF $ Chime ()

peaWhistle :: Whistles ()
peaWhistle = liftF $ PeaWhistle ()

steamWhistle …