ghc-mod/Language/Haskell/GhcMod/Monad.hs
2015-02-08 12:43:35 +01:00

486 lines
14 KiB
Haskell

{-# LANGUAGE CPP, GeneralizedNewtypeDeriving, FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts, MultiParamTypeClasses, RankNTypes #-}
{-# LANGUAGE TypeFamilies, UndecidableInstances, RecordWildCards #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Language.Haskell.GhcMod.Monad (
-- * Monad Types
GhcModT
, IOish
-- ** Environment, state and logging
, GhcModEnv(..)
, newGhcModEnv
, GhcModState(..)
, defaultState
, CompilerMode(..)
, GhcModLog
, GhcModError(..)
-- * Monad utilities
, runGhcModT
, runGhcModT'
, hoistGhcModT
-- ** Accessing 'GhcModEnv' and 'GhcModState'
, gmsGet
, gmsPut
, options
, cradle
, getCompilerMode
, setCompilerMode
, withOptions
, withTempSession
, overrideGhcUserOptions
-- ** Re-exporting convenient stuff
, liftIO
, module Control.Monad.Reader.Class
, module Control.Monad.Journal.Class
) where
#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
import Language.Haskell.GhcMod.Types
import Language.Haskell.GhcMod.Error
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
import DynFlags
import GHC
import qualified GHC as G
import GHC.Paths (libdir)
import GhcMonad hiding (withTempSession)
#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 DIFFERENT_MONADIO
import Control.Monad.Trans.Class (lift)
import qualified Control.Monad.IO.Class
import Data.Monoid (Monoid)
#endif
import Control.Applicative (Alternative)
import Control.Arrow (first)
import Control.Monad (MonadPlus, void)
#if !MIN_VERSION_monad_control(1,0,0)
import Control.Monad (liftM)
#endif
import Control.Monad.Base (MonadBase, liftBase)
-- Monad transformer stuff
import Control.Monad.Trans.Control (MonadBaseControl(..), StM, liftBaseWith,
control, liftBaseOp, liftBaseOp_)
import Control.Monad.Trans.Class
import Control.Monad.Reader.Class
import Control.Monad.Writer.Class (MonadWriter)
import Control.Monad.State.Class (MonadState(..))
import Control.Monad.Error (ErrorT, runErrorT)
import Control.Monad.Reader (ReaderT, runReaderT)
import Control.Monad.State.Strict (StateT, runStateT)
import Control.Monad.Trans.Journal (JournalT, runJournalT)
#ifdef MONADIO_INSTANCES
import Control.Monad.Trans.Maybe (MaybeT)
import Control.Monad.Error (Error(..))
#endif
import Control.Monad.Journal.Class
import Data.Maybe (isJust)
import Data.IORef (IORef, readIORef, writeIORef, newIORef)
import System.Directory (getCurrentDirectory)
----------------------------------------------------------------
data GhcModEnv = GhcModEnv {
gmGhcSession :: !(IORef HscEnv)
, gmOptions :: Options
, gmCradle :: Cradle
}
type GhcModLog = ()
data GhcModState = GhcModState {
gmCompilerMode :: CompilerMode
} deriving (Eq,Show,Read)
data CompilerMode = Simple | Intelligent deriving (Eq,Show,Read)
defaultState :: GhcModState
defaultState = GhcModState Simple
----------------------------------------------------------------
-- | This is basically a newtype wrapper around 'StateT', 'ErrorT', 'JournalT'
-- and 'ReaderT' with custom instances for 'GhcMonad' and it's constraints that
-- means you can run (almost) all functions from the GHC API on top of 'GhcModT'
-- transparently.
--
-- The inner monad @m@ should have instances for 'MonadIO' and
-- 'MonadBaseControl' 'IO', in the common case this is simply 'IO'. Most @mtl@
-- monads already have 'MonadBaseControl' 'IO' instances, see the
-- @monad-control@ package.
newtype GhcModT m a = GhcModT {
unGhcModT :: StateT GhcModState
(ErrorT GhcModError
(JournalT GhcModLog
(ReaderT GhcModEnv m) ) ) a
} deriving ( Functor
, Applicative
, Alternative
, Monad
, MonadPlus
#if DIFFERENT_MONADIO
, Control.Monad.IO.Class.MonadIO
#endif
, MonadReader GhcModEnv -- TODO: make MonadReader instance
-- pass-through like MonadState
, MonadWriter w
, MonadError GhcModError
)
instance MonadIO m => MonadIO (GhcModT m) where
liftIO action = do
res <- GhcModT . liftIO . liftIO . liftIO . liftIO $ try action
case res of
Right a -> return a
Left e | isIOError e ->
throwError $ GMEIOException (fromEx e :: IOError)
Left e | isGhcModError e ->
throwError $ (fromEx e :: GhcModError)
Left e -> throw e
where
fromEx :: Exception e => SomeException -> e
fromEx se = let Just e = fromException se in e
isIOError se =
case fromException se of
Just (_ :: IOError) -> True
Nothing -> False
isGhcModError se =
case fromException se of
Just (_ :: GhcModError) -> True
Nothing -> False
instance MonadTrans (GhcModT) where
lift = GhcModT . lift . lift . lift . lift
instance MonadState s m => MonadState s (GhcModT m) where
get = GhcModT $ lift $ lift $ lift get
put = GhcModT . lift . lift . lift . put
state = GhcModT . lift . lift . lift . state
#if MONADIO_INSTANCES
instance MonadIO m => MonadIO (StateT s m) where
liftIO = lift . liftIO
instance MonadIO m => MonadIO (ReaderT r m) where
liftIO = lift . liftIO
instance (Monoid w, MonadIO m) => MonadIO (JournalT w m) where
liftIO = lift . liftIO
instance (Error e, MonadIO m) => MonadIO (ErrorT e m) where
liftIO = lift . liftIO
instance MonadIO m => MonadIO (MaybeT m) where
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 :: (IOish m, GhcMonad m, MonadError GhcModError m)
=> Options
-> Cradle
-> m ()
initializeFlagsWithCradle opt c
| cabal = withCabal
| otherwise = withSandbox
where
mCabalFile = cradleCabalFile c
cabal = isJust mCabalFile
ghcopts = ghcUserOptions opt
withCabal = do
let Just cabalFile = mCabalFile
pkgDesc <- parseCabalFile c cabalFile
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, rdir) = (cradleCurrentDir c, cradleRootDir c)
initSession :: GhcMonad m
=> Build
-> Options
-> CompilerOptions
-> m ()
initSession build Options {..} CompilerOptions {..} = do
df <- G.getSessionDynFlags
void $ G.setSessionDynFlags =<< addCmdOpts ghcOptions
( setModeSimple
$ 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
}
cleanupGhcModEnv :: GhcModEnv -> IO ()
cleanupGhcModEnv env = cleanupCradle $ gmCradle env
-- | Run a @GhcModT m@ computation.
runGhcModT :: IOish m
=> Options
-> GhcModT m a
-> m (Either GhcModError a, GhcModLog)
runGhcModT opt action = gbracket newEnv delEnv $ \env -> do
r <- first (fst <$>) <$> (runGhcModT' env defaultState $ do
dflags <- getSessionDynFlags
defaultCleanupHandler dflags $ do
initializeFlagsWithCradle opt (gmCradle env)
action)
return r
where
newEnv = liftBase $ newGhcModEnv opt =<< getCurrentDirectory
delEnv = liftBase . cleanupGhcModEnv
-- | @hoistGhcModT result@. Embed a GhcModT computation's result into a GhcModT
-- computation. Note that if the computation that returned @result@ modified the
-- state part of GhcModT this cannot be restored.
hoistGhcModT :: IOish m
=> (Either GhcModError a, GhcModLog)
-> GhcModT m a
hoistGhcModT (r,l) = do
GhcModT (lift $ lift $ journal l) >> case r of
Left e -> throwError e
Right a -> return a
-- | 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
-> m (Either GhcModError (a, GhcModState), GhcModLog)
runGhcModT' r s a = do
(res, w') <-
flip runReaderT r $ runJournalT $ runErrorT $
runStateT (unGhcModT $ initGhcMonad (Just libdir) >> a) s
return (res, w')
----------------------------------------------------------------
-- | 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
----------------------------------------------------------------
gmeAsk :: IOish m => GhcModT m GhcModEnv
gmeAsk = ask
gmsGet :: IOish m => GhcModT m GhcModState
gmsGet = GhcModT get
gmsPut :: IOish m => GhcModState -> GhcModT m ()
gmsPut = GhcModT . put
options :: IOish m => GhcModT m Options
options = gmOptions <$> gmeAsk
cradle :: IOish m => GhcModT m Cradle
cradle = gmCradle <$> gmeAsk
getCompilerMode :: IOish m => GhcModT m CompilerMode
getCompilerMode = gmCompilerMode <$> gmsGet
setCompilerMode :: IOish m => CompilerMode -> GhcModT m ()
setCompilerMode mode = (\s -> gmsPut s { gmCompilerMode = mode } ) =<< gmsGet
----------------------------------------------------------------
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
#if MIN_VERSION_monad_control(1,0,0)
instance (MonadBaseControl IO m) => MonadBaseControl IO (GhcModT m) where
type StM (GhcModT m) a =
StM (StateT GhcModState
(ErrorT GhcModError
(JournalT GhcModLog
(ReaderT GhcModEnv m) ) ) ) a
liftBaseWith f = GhcModT . liftBaseWith $ \runInBase ->
f $ runInBase . unGhcModT
restoreM = GhcModT . restoreM
{-# INLINE liftBaseWith #-}
{-# INLINE restoreM #-}
#else
instance (MonadBaseControl IO m) => MonadBaseControl IO (GhcModT m) where
newtype StM (GhcModT m) a = StGhcMod {
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 #-}
#endif
-- 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