ghc-mod/Language/Haskell/GhcMod/Monad.hs
Daniel Gröber f0bfcb8811 Use GhcModT everywhere and remove the GhcMod alias
Not doing this makes having GhcModT pretty pointless as users of the
library wouldn't be able to use custom inner monads as evey function for
dealing with GhcModT's would be constraint to (GhcModT IO) thus only
allowing IO as the inner monad.
2014-07-15 01:03:56 +02:00

298 lines
8.8 KiB
Haskell

{-# LANGUAGE CPP, GeneralizedNewtypeDeriving, FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts, MultiParamTypeClasses, RankNTypes #-}
{-# LANGUAGE TypeFamilies, UndecidableInstances, RecordWildCards #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Language.Haskell.GhcMod.Monad (
GhcModT
, IOish
, GhcModEnv(..)
, GhcModWriter
, GhcModState(..)
, runGhcModT'
, runGhcModT
, newGhcModEnv
, withErrorHandler
, toGhcMod
, options
, cradle
, module Control.Monad.Reader.Class
, module Control.Monad.Writer.Class
, module Control.Monad.State.Class
) where
import Language.Haskell.GhcMod.Types
import Language.Haskell.GhcMod.Cradle
import Language.Haskell.GhcMod.DynFlags
import Language.Haskell.GhcMod.GhcPkg
import Language.Haskell.GhcMod.GHCChoice
import Language.Haskell.GhcMod.CabalApi
import qualified Language.Haskell.GhcMod.Gap as Gap
import DynFlags
import Exception
import GHC
import qualified GHC as G
import GHC.Paths (libdir)
import GhcMonad
#if __GLASGOW_HASKELL__ <= 702
import HscTypes
#endif
-- MonadUtils of GHC 7.6 or earlier defines its own MonadIO.
-- RWST does not automatically become an instance of MonadIO.
-- MonadUtils of GHC 7.8 or later imports MonadIO in Monad.Control.IO.Class.
-- So, RWST automatically becomes an instance of MonadIO.
import MonadUtils
#if __GLASGOW_HASKELL__ < 708
-- To make RWST an instance of MonadIO.
import Control.Monad.Trans.Class (lift)
import Data.Monoid (Monoid)
#endif
import Control.Applicative (Alternative)
import Control.Monad (MonadPlus, liftM, void)
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
import Data.Maybe (fromJust, isJust)
import Data.IORef (IORef, readIORef, writeIORef, newIORef)
import System.Exit (exitSuccess)
import System.IO (hPutStr, hPrint, stderr)
import System.Directory (getCurrentDirectory)
----------------------------------------------------------------
data GhcModEnv = GhcModEnv {
gmGhcSession :: !(IORef HscEnv)
, gmOptions :: Options
, gmCradle :: Cradle
}
data GhcModState = GhcModState
defaultState :: GhcModState
defaultState = GhcModState
type GhcModWriter = ()
----------------------------------------------------------------
type IOish m = (Functor m, MonadIO m, MonadBaseControl IO m)
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
instance (Monoid w, MonadIO m) => MonadIO (RWST r w s m) where
-- liftIO :: MonadIO m => IO a -> m a
liftIO = lift . liftIO
#endif
----------------------------------------------------------------
-- | Initialize the 'DynFlags' relating to the compilation of a single
-- file or GHC session according to the 'Cradle' and 'Options'
-- provided.
initializeFlagsWithCradle :: GhcMonad m
=> Options
-> Cradle
-> m ()
initializeFlagsWithCradle opt c
| cabal = withCabal |||> withSandbox
| otherwise = withSandbox
where
mCradleFile = cradleCabalFile c
cabal = isJust mCradleFile
ghcopts = ghcOpts opt
withCabal = do
pkgDesc <- liftIO $ parseCabalFile $ fromJust mCradleFile
compOpts <- liftIO $ getCompilerOptions ghcopts c pkgDesc
initSession CabalPkg opt compOpts
withSandbox = initSession SingleFile opt compOpts
where
importDirs = [".","..","../..","../../..","../../../..","../../../../.."]
pkgOpts = ghcDbStackOpts $ cradlePkgDbStack c
compOpts
| null pkgOpts = CompilerOptions ghcopts importDirs []
| otherwise = CompilerOptions (ghcopts ++ pkgOpts) [wdir,rdir] []
wdir = cradleCurrentDir c
rdir = cradleRootDir c
initSession :: GhcMonad m
=> Build
-> Options
-> CompilerOptions
-> m ()
initSession build Options {..} CompilerOptions {..} = do
df <- G.getSessionDynFlags
void $ G.setSessionDynFlags =<< (addCmdOpts ghcOptions
$ setLinkerOptions
$ setIncludeDirs includeDirs
$ setBuildEnv build
$ setEmptyLogger
$ Gap.addPackageFlags depPackages df)
----------------------------------------------------------------
runGhcModT' :: IOish m
=> GhcModEnv
-> GhcModState
-> 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
newGhcModEnv opt dir = do
session <- newIORef (error "empty session")
c <- findCradle' dir
return GhcModEnv {
gmGhcSession = session
, gmOptions = opt
, gmCradle = c
}
runGhcModT :: IOish 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
initializeFlagsWithCradle opt (gmCradle env)
action
return a
----------------------------------------------------------------
withErrorHandler :: IOish m => String -> GhcModT m a -> GhcModT m a
withErrorHandler label = ghandle ignore
where
ignore :: IOish m => SomeException -> GhcModT m a
ignore e = liftIO $ do
hPutStr stderr $ label ++ ":0:0:Error:"
hPrint stderr e
exitSuccess
-- | This is only a transitional mechanism don't use it for new code.
toGhcMod :: IOish m => Ghc a -> GhcModT m a
toGhcMod a = do
s <- gmGhcSession <$> ask
liftIO $ unGhc a $ Session s
----------------------------------------------------------------
options :: IOish m => GhcModT m Options
options = gmOptions <$> ask
cradle :: IOish m => GhcModT m Cradle
cradle = gmCradle <$> ask
instance (MonadBaseControl IO m) => MonadBase IO (GhcModT m) where
liftBase = GhcModT . liftBase
instance (MonadBaseControl IO m) => MonadBaseControl IO (GhcModT m) where
newtype StM (GhcModT m) a = StGhcMod {
unStGhcMod :: StM (RWST GhcModEnv () GhcModState m) a }
liftBaseWith f = GhcModT . liftBaseWith $ \runInBase ->
f $ liftM StGhcMod . runInBase . unGhcModT
restoreM = GhcModT . restoreM . unStGhcMod
{-# INLINE liftBaseWith #-}
{-# INLINE restoreM #-}
-- 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 (Functor m, MonadIO m, MonadBaseControl IO m)
=> HasDynFlags (GhcModT m) where
getDynFlags = getSessionDynFlags
#endif
instance (MonadIO m, MonadBaseControl IO m)
=> ExceptionMonad (GhcModT m) where
gcatch act handler = control $ \run ->
run act `gcatch` (run . handler)
gmask = liftBaseOp gmask . liftRestore
where liftRestore f r = f $ liftBaseOp_ r