ghc-mod/Language/Haskell/GhcMod/Monad.hs

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{-# LANGUAGE CPP, GeneralizedNewtypeDeriving, FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts, MultiParamTypeClasses, RankNTypes #-}
{-# LANGUAGE TypeFamilies, UndecidableInstances, RecordWildCards #-}
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{-# OPTIONS_GHC -fno-warn-orphans #-}
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module Language.Haskell.GhcMod.Monad (
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-- * Monad Types
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GhcModT
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, IOish
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-- ** Environment, state and logging
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, GhcModEnv(..)
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, newGhcModEnv
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, GhcModState(..)
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, defaultState
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, CompilerMode(..)
, GhcModLog
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, GhcModError(..)
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-- * Monad utilities
, runGhcModT
, runGhcModT'
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-- ** Accessing 'GhcModEnv' and 'GhcModState'
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, gmsGet
, gmsPut
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, options
, cradle
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, getCompilerMode
, setCompilerMode
, withOptions
, withTempSession
, overrideGhcUserOptions
-- ** Re-exporting convenient stuff
, liftIO
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, module Control.Monad.Reader.Class
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, module Control.Monad.Journal.Class
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) where
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#if __GLASGOW_HASKELL__ < 708
-- 'CoreMonad.MonadIO' and 'Control.Monad.IO.Class.MonadIO' are different
-- classes before ghc 7.8
#define DIFFERENT_MONADIO 1
-- RWST doen't have a MonadIO instance before ghc 7.8
#define MONADIO_INSTANCES 1
#endif
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import Language.Haskell.GhcMod.Types
import Language.Haskell.GhcMod.Cradle
import Language.Haskell.GhcMod.DynFlags
import Language.Haskell.GhcMod.GhcPkg
import Language.Haskell.GhcMod.CabalApi
import qualified Language.Haskell.GhcMod.Gap as Gap
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import DynFlags
import Exception
import GHC
import qualified GHC as G
import GHC.Paths (libdir)
import GhcMonad hiding (withTempSession)
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#if __GLASGOW_HASKELL__ <= 702
import HscTypes
#endif
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-- 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
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#if DIFFERENT_MONADIO
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import Control.Monad.Trans.Class (lift)
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import qualified Control.Monad.IO.Class
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import Data.Monoid (Monoid)
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#endif
import Control.Applicative (Alternative)
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import Control.Arrow (first)
import Control.Monad (MonadPlus, void, liftM)
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import Control.Monad.Base (MonadBase, liftBase)
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-- Monad transformer stuff
import Control.Monad.Trans.Control (MonadBaseControl(..), StM, liftBaseWith,
control, liftBaseOp, liftBaseOp_)
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import Control.Monad.Trans.Class
import Control.Monad.Reader.Class
import Control.Monad.Writer.Class (MonadWriter)
import Control.Monad.State.Class (MonadState(..))
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import Control.Monad.Error (MonadError, ErrorT, runErrorT)
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import Control.Monad.Reader (ReaderT, runReaderT)
import Control.Monad.State.Strict (StateT, runStateT)
import Control.Monad.Trans.Journal (JournalT, runJournalT)
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#ifdef MONADIO_INSTANCES
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import Control.Monad.Trans.Maybe (MaybeT)
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import Control.Monad.Error (Error(..))
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#endif
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import Control.Monad.Journal.Class
import Data.Maybe (fromJust, isJust)
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import Data.IORef (IORef, readIORef, writeIORef, newIORef)
import System.Directory (getCurrentDirectory)
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----------------------------------------------------------------
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data GhcModEnv = GhcModEnv {
gmGhcSession :: !(IORef HscEnv)
, gmOptions :: Options
, gmCradle :: Cradle
}
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type GhcModLog = ()
data GhcModState = GhcModState {
gmCompilerMode :: CompilerMode
} deriving (Eq,Show,Read)
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data CompilerMode = Simple | Intelligent deriving (Eq,Show,Read)
defaultState :: GhcModState
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defaultState = GhcModState Simple
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----------------------------------------------------------------
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-- | A constraint alias (-XConstraintKinds) to make functions dealing with
-- 'GhcModT' somewhat cleaner.
--
-- Basicially an @IOish m => m@ is a 'Monad' supporting arbitrary 'IO' and
-- exception handling. Usually this will simply be 'IO' but we parametrise it in
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-- the exported API so users have the option to use a custom inner monad.
type IOish m = (Functor m, MonadIO m, MonadBaseControl IO m)
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-- | The GhcMod monad transformer data type. This is basically a newtype wrapper
-- around 'StateT', 'ErrorT', 'JournalT' and 'ReaderT' with custom instances for
-- 'GhcMonad' and it's constraints.
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--
-- The inner monad should have instances for 'MonadIO' and 'MonadBaseControl'
-- 'IO'. Most @mtl@ monads already have 'MonadBaseControl' 'IO' instances, see
-- the @monad-control@ package.
newtype GhcModT m a = GhcModT {
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unGhcModT :: StateT GhcModState
(ErrorT GhcModError
(JournalT GhcModLog
(ReaderT GhcModEnv m) ) ) a
} deriving ( Functor
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, Applicative
, Alternative
, Monad
, MonadPlus
, MonadIO
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#if DIFFERENT_MONADIO
, Control.Monad.IO.Class.MonadIO
#endif
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, MonadReader GhcModEnv -- TODO: make MonadReader instance
-- pass-through like MonadState
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, MonadWriter w
, MonadError GhcModError
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)
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instance MonadTrans GhcModT where
lift = GhcModT . lift . lift . lift . lift
instance MonadState s m => MonadState s (GhcModT m) where
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get = GhcModT $ lift $ lift $ lift get
put = GhcModT . lift . lift . lift . put
state = GhcModT . lift . lift . lift . state
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#if MONADIO_INSTANCES
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instance MonadIO m => MonadIO (StateT s m) where
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liftIO = lift . liftIO
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instance MonadIO m => MonadIO (ReaderT r m) where
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liftIO = lift . liftIO
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instance (Monoid w, MonadIO m) => MonadIO (JournalT w m) where
liftIO = lift . liftIO
instance (Error e, MonadIO m) => MonadIO (ErrorT e m) where
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liftIO = lift . liftIO
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instance MonadIO m => MonadIO (MaybeT m) where
liftIO = lift . liftIO
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#endif
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----------------------------------------------------------------
-- | Initialize the 'DynFlags' relating to the compilation of a single
-- file or GHC session according to the 'Cradle' and 'Options'
-- provided.
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initializeFlagsWithCradle :: (GhcMonad m, MonadError GhcModError m)
=> Options
-> Cradle
-> m ()
initializeFlagsWithCradle opt c
| cabal = withCabal
| otherwise = withSandbox
where
mCradleFile = cradleCabalFile c
cabal = isJust mCradleFile
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ghcopts = ghcUserOptions opt
withCabal = do
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pkgDesc <- parseCabalFile $ fromJust mCradleFile
compOpts <- 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
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void $ G.setSessionDynFlags =<< addCmdOpts ghcOptions
( setModeSimple
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$ Gap.setFlags
$ setIncludeDirs includeDirs
$ setBuildEnv build
$ setEmptyLogger
$ Gap.addPackageFlags depPackages df)
----------------------------------------------------------------
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
}
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-- | Run a @GhcModT m@ computation.
runGhcModT :: IOish m
=> Options
-> GhcModT m a
-> m (Either GhcModError a, GhcModLog)
runGhcModT opt action = do
env <- liftBase $ newGhcModEnv opt =<< getCurrentDirectory
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first (fst <$>) <$> (runGhcModT' env defaultState $ do
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dflags <- getSessionDynFlags
defaultCleanupHandler dflags $ do
initializeFlagsWithCradle opt (gmCradle env)
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action)
-- | Run a computation inside @GhcModT@ providing the RWST environment and
-- initial state. This is a low level function, use it only if you know what to
-- do with 'GhcModEnv' and 'GhcModState'.
--
-- You should probably look at 'runGhcModT' instead.
runGhcModT' :: IOish m
=> GhcModEnv
-> GhcModState
-> GhcModT m a
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-> m (Either GhcModError (a, GhcModState), GhcModLog)
runGhcModT' r s a = do
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(res, w') <-
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flip runReaderT r $ runJournalT $ runErrorT $
runStateT (unGhcModT $ initGhcMonad (Just libdir) >> a) s
return (res, w')
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----------------------------------------------------------------
-- | Make a copy of the 'gmGhcSession' IORef, run the action and restore the
-- original 'HscEnv'.
withTempSession :: IOish m => GhcModT m a -> GhcModT m a
withTempSession action = do
session <- gmGhcSession <$> ask
savedHscEnv <- liftIO $ readIORef session
a <- action
liftIO $ writeIORef session savedHscEnv
return a
-- | This is a very ugly workaround don't use it.
overrideGhcUserOptions :: IOish m => ([GHCOption] -> GhcModT m b) -> GhcModT m b
overrideGhcUserOptions action = withTempSession $ do
env <- ask
opt <- options
let ghcOpts = ghcUserOptions opt
opt' = opt { ghcUserOptions = [] }
initializeFlagsWithCradle opt' (gmCradle env)
action ghcOpts
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----------------------------------------------------------------
gmsGet :: IOish m => GhcModT m GhcModState
gmsGet = GhcModT get
gmsPut :: IOish m => GhcModState -> GhcModT m ()
gmsPut = GhcModT . put
options :: IOish m => GhcModT m Options
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options = gmOptions <$> ask
cradle :: IOish m => GhcModT m Cradle
cradle = gmCradle <$> ask
getCompilerMode :: IOish m => GhcModT m CompilerMode
getCompilerMode = gmCompilerMode <$> gmsGet
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setCompilerMode :: IOish m => CompilerMode -> GhcModT m ()
setCompilerMode mode = (\s -> gmsPut s { gmCompilerMode = mode } ) =<< gmsGet
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----------------------------------------------------------------
withOptions :: IOish m => (Options -> Options) -> GhcModT m a -> GhcModT m a
withOptions changeOpt action = local changeEnv action
where
changeEnv e = e { gmOptions = changeOpt opt }
where
opt = gmOptions e
----------------------------------------------------------------
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 {
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unStGhcMod :: StM (StateT GhcModState
(ErrorT GhcModError
(JournalT GhcModLog
(ReaderT GhcModEnv 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
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#if __GLASGOW_HASKELL__ >= 706
instance (Functor m, MonadIO m, MonadBaseControl IO m)
=> HasDynFlags (GhcModT m) where
getDynFlags = getSessionDynFlags
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#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