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|
{-# LANGUAGE NoImplicitPrelude #-}
{-# OPTIONS_HADDOCK hide #-}
-----------------------------------------------------------------------------
-- |
-- Module : GHC.GHCi
-- Copyright : (c) The University of Glasgow 2012
-- License : see libraries/base/LICENSE
--
-- Maintainer : cvs-ghc@haskell.org
-- Stability : internal
-- Portability : non-portable (GHC Extensions)
--
-- The GHCi Monad lifting interface.
--
-- EXPERIMENTAL! DON'T USE.
--
-----------------------------------------------------------------------------
module GHC.GHCi {-# WARNING "This is an unstable interface." #-} (
GHCiSandboxIO(..), NoIO()
) where
import GHC.Base (IO(), Monad, Functor(fmap), Applicative(..), (>>=), return, id, (.), ap)
-- | A monad that can execute GHCi statements by lifting them out of
-- m into the IO monad. (e.g state monads)
class (Monad m) => GHCiSandboxIO m where
ghciStepIO :: m a -> IO a
instance GHCiSandboxIO IO where
ghciStepIO = id
-- | A monad that doesn't allow any IO.
newtype NoIO a = NoIO { noio :: IO a }
instance Functor NoIO where
fmap f (NoIO a) = NoIO (fmap f a)
instance Applicative NoIO where
pure = return
(<*>) = ap
instance Monad NoIO where
return a = NoIO (return a)
(>>=) k f = NoIO (noio k >>= noio . f)
instance GHCiSandboxIO NoIO where
ghciStepIO = noio
|
