Make GhcMod a special case of GhcModT

i.e. turn GhcMod into a monad transformer
This commit is contained in:
Daniel Gröber 2014-07-11 04:51:11 +02:00
parent 56ad1a3c8c
commit 320b2243a2

View File

@ -1,14 +1,18 @@
{-# LANGUAGE CPP, GeneralizedNewtypeDeriving, FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses, RankNTypes, TypeFamilies #-}
{-# LANGUAGE FlexibleContexts, MultiParamTypeClasses, RankNTypes #-}
{-# LANGUAGE TypeFamilies, UndecidableInstances #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Language.Haskell.GhcMod.Monad (
GhcMod
, GhcModT
, GhcModEnv(..)
, GhcModWriter
, GhcModState(..)
, runGhcMod'
, runGhcMod
, runGhcModT'
, runGhcModT
, newGhcModEnv
, withErrorHandler
, toGhcMod
@ -44,10 +48,13 @@ import Control.Monad.Trans.Class (lift)
import Data.Monoid (Monoid)
#endif
import Control.Monad (liftM)
import Control.Applicative (Alternative)
import Control.Monad (MonadPlus, liftM)
import Control.Monad.Base (MonadBase,liftBase)
import Control.Monad.Reader.Class
import Control.Monad.State.Class
import Control.Monad.Trans.Class
import Control.Monad.Trans.Control (MonadBaseControl(..), StM, liftBaseWith, control, liftBaseOp, liftBaseOp_)
import Control.Monad.Trans.RWS.Lazy (RWST(..),runRWST)
import Control.Monad.Writer.Class
@ -73,16 +80,20 @@ defaultState = GhcModState
type GhcModWriter = ()
----------------------------------------------------------------
type GhcMod a = GhcModT IO a
newtype GhcMod a = GhcMod {
unGhcMod :: RWST GhcModEnv GhcModWriter GhcModState IO a
newtype GhcModT m a = GhcModT {
unGhcModT :: RWST GhcModEnv GhcModWriter GhcModState m a
} deriving (Functor
,Applicative
,Alternative
,Monad
,MonadPlus
,MonadIO
,MonadReader GhcModEnv
,MonadWriter GhcModWriter
,MonadState GhcModState
,MonadTrans
)
#if __GLASGOW_HASKELL__ < 708
@ -92,13 +103,13 @@ instance (Monoid w, MonadIO m) => MonadIO (RWST r w s m) where
#endif
----------------------------------------------------------------
runGhcMod' :: GhcModEnv
runGhcModT' :: (MonadIO m, MonadBaseControl IO m)
=> GhcModEnv
-> GhcModState
-> GhcMod a
-> IO (a,(GhcModState, GhcModWriter))
runGhcMod' r s a = do
(a', s',w) <- runRWST (unGhcMod $ initGhcMonad (Just libdir) >> a) r s
-> GhcModT m a
-> m (a,(GhcModState, GhcModWriter))
runGhcModT' r s a = do
(a',s',w) <- runRWST (unGhcModT $ initGhcMonad (Just libdir) >> a) r s
return (a',(s',w))
newGhcModEnv :: Options -> FilePath -> IO GhcModEnv
@ -111,16 +122,24 @@ newGhcModEnv opt dir = do
, gmCradle = c
}
runGhcMod :: Options -> GhcMod a -> IO a
runGhcMod opt action = do
env <- liftIO $ newGhcModEnv opt =<< getCurrentDirectory
(a,(_,_)) <- runGhcMod' env defaultState $ do
runGhcModT :: (MonadIO m, MonadBaseControl IO m) => Options -> GhcModT m a -> m a
runGhcModT opt action = do
env <- liftBase $ newGhcModEnv opt =<< getCurrentDirectory
(a,(_,_)) <- runGhcModT' env defaultState $ do
dflags <- getSessionDynFlags
defaultCleanupHandler dflags $ do
toGhcMod $ initializeFlagsWithCradle opt (gmCradle env)
initializeFlagsWithCradle opt (gmCradle env)
action
return a
runGhcMod' :: GhcModEnv
-> GhcModState
-> GhcModT IO a
-> IO (a,(GhcModState, GhcModWriter))
runGhcMod' = runGhcModT'
runGhcMod :: Options -> GhcMod a -> IO a
runGhcMod = runGhcModT
----------------------------------------------------------------
withErrorHandler :: String -> GhcMod a -> GhcMod a
@ -133,7 +152,7 @@ withErrorHandler label = ghandle ignore
exitSuccess
-- | This is only a transitional mechanism don't use it for new code.
toGhcMod :: Ghc a -> GhcMod a
toGhcMod :: (Functor m, MonadIO m) => Ghc a -> GhcModT m a
toGhcMod a = do
s <- gmGhcSession <$> ask
liftIO $ unGhc a $ Session s
@ -146,30 +165,90 @@ options = gmOptions <$> ask
cradle :: GhcMod Cradle
cradle = gmCradle <$> ask
instance MonadBase IO GhcMod where
liftBase = GhcMod . liftBase
instance MonadBaseControl IO GhcMod where
newtype StM GhcMod a = StGhcMod {
unStGhcMod :: StM (RWST GhcModEnv () GhcModState IO) a }
instance (MonadBaseControl IO m) => MonadBase IO (GhcModT m) where
liftBase = GhcModT . liftBase
liftBaseWith f = GhcMod . liftBaseWith $ \runInBase ->
f $ liftM StGhcMod . runInBase . unGhcMod
instance (MonadBaseControl IO m) => MonadBaseControl IO (GhcModT m) where
newtype StM (GhcModT m) a = StGhcMod {
unStGhcMod :: StM (RWST GhcModEnv () GhcModState m) a }
restoreM = GhcMod . restoreM . unStGhcMod
liftBaseWith f = GhcModT . liftBaseWith $ \runInBase ->
f $ liftM StGhcMod . runInBase . unGhcModT
restoreM = GhcModT . restoreM . unStGhcMod
{-# INLINE liftBaseWith #-}
{-# INLINE restoreM #-}
instance GhcMonad GhcMod where
getSession = liftIO . readIORef . gmGhcSession =<< ask
setSession a = liftIO . flip writeIORef a . gmGhcSession =<< ask
-- GHC cannot prove the following instances to be decidable automatically using
-- the FlexibleContexts extension as they violate the second Paterson Condition,
-- namely that: The assertion has fewer constructors and variables (taken
-- together and counting repetitions) than the head. Specifically the
-- @MonadBaseControl IO m@ constraint is causing this violation.
--
-- Proof of termination:
--
-- Assuming all constraints containing the variable `m' exist and are decidable
-- we show termination by manually replacing the current set of constraints with
-- their own set of constraints and show that this, after a finite number of
-- steps, results in the empty set, i.e. not having to check any more
-- constraints.
--
-- We start by setting the constraints to be those immediate constraints of the
-- instance declaration which cannot be proven decidable automatically for the
-- type under consideration.
--
-- @
-- { MonadBaseControl IO m }
-- @
--
-- Classes used:
--
-- * @class MonadBase b m => MonadBaseControl b m@
--
-- @
-- { MonadBase IO m }
-- @
--
-- Classes used:
--
-- * @class (Applicative b, Applicative m, Monad b, Monad m) => MonadBase b m@
--
-- @
-- { Applicative IO, Applicative m, Monad IO, Monad m }
-- @
--
-- Classes used:
--
-- * @class Monad m@
-- * @class Applicative f => Functor f@
--
-- @
-- { Functor m }
-- @
--
-- Classes used:
--
-- * @class Functor f@
--
-- @
-- { }
-- @
-- ∎
instance (Functor m, MonadIO m, MonadBaseControl IO m)
=> GhcMonad (GhcModT m) where
getSession = (liftIO . readIORef) . gmGhcSession =<< ask
setSession a = (liftIO . flip writeIORef a) . gmGhcSession =<< ask
#if __GLASGOW_HASKELL__ >= 706
instance HasDynFlags GhcMod where
instance (Functor m, MonadIO m, MonadBaseControl IO m)
=> HasDynFlags (GhcModT m) where
getDynFlags = getSessionDynFlags
#endif
instance ExceptionMonad GhcMod where
instance (MonadIO m, MonadBaseControl IO m)
=> ExceptionMonad (GhcModT m) where
gcatch act handler = control $ \run ->
run act `gcatch` (run . handler)