ghc-mod/Language/Haskell/GhcMod/Monad.hs
2014-07-18 14:55:21 +09:00

388 lines
11 KiB
Haskell

{-# LANGUAGE CPP, GeneralizedNewtypeDeriving, FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts, MultiParamTypeClasses, RankNTypes #-}
{-# LANGUAGE TypeFamilies, UndecidableInstances, RecordWildCards #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Language.Haskell.GhcMod.Monad (
-- * Monad Types
GhcMod
, GhcModT
, IOish
-- ** Environment, state and logging
, GhcModEnv(..)
, newGhcModEnv
, GhcModState
, defaultState
, Mode(..)
, GhcModWriter
-- * Monad utilities
, runGhcMod
, runGhcModT
, runGhcModT'
, withErrorHandler
-- ** Conversion
, liftGhcMod
, toGhcMod
-- ** Accessing 'GhcModEnv' and 'GhcModState'
, options
, cradle
, getMode
, setMode
-- ** Exporting convenient modules
, module Control.Monad.Reader.Class
, module Control.Monad.Writer.Class
, module Control.Monad.State.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.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 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.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
#if __GLASGOW_HASKELL__ < 708
import Control.Monad.Trans.Maybe
#endif
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 Control.Monad.Error (Error(..), ErrorT(..), MonadError)
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 Mode deriving (Eq,Show,Read)
data Mode = Simple | Intelligent deriving (Eq,Show,Read)
defaultState :: GhcModState
defaultState = GhcModState Simple
type GhcModWriter = ()
data GhcModError = GMENoMsg
| GMEString String
| GMECabal
| GMEGhc
deriving (Eq,Show,Read)
instance Error GhcModError where
noMsg = GMENoMsg
strMsg = GMEString
----------------------------------------------------------------
type IOish m = (Functor m, MonadIO m, MonadBaseControl IO m)
type GhcMod a = GhcModT (ErrorT GhcModError IO) a
newtype GhcModT m a = GhcModT {
unGhcModT :: RWST GhcModEnv GhcModWriter GhcModState m a
} deriving (Functor
, Applicative
, Alternative
, Monad
, MonadPlus
, MonadIO
#if DIFFERENT_MONADIO
, Control.Monad.IO.Class.MonadIO
#endif
, MonadReader GhcModEnv
, MonadWriter GhcModWriter
, MonadState GhcModState
, MonadTrans
)
deriving instance MonadError GhcModError m => MonadError GhcModError (GhcModT m)
#if MONADIO_INSTANCES
instance (Monoid w, MonadIO m) => MonadIO (RWST r w s 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 :: 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
( 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
}
-- | Run a @GhcModT m@ computation, i.e. one with a custom underlying monad.
--
-- You probably don't want this, look at 'runGhcMod' instead.
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
-- | 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 (a,(GhcModState, GhcModWriter))
runGhcModT' r s a = do
(a',s',w) <- runRWST (unGhcModT $ initGhcMonad (Just libdir) >> a) r s
return (a',(s',w))
-- | Run a 'GhcMod' computation. If you want an underlying monad other than
-- 'ErrorT e IO' you should look at 'runGhcModT'
runGhcMod :: Options
-> GhcMod a
-> IO (Either GhcModError a)
runGhcMod o a =
runErrorT $ runGhcModT o a
liftErrorT :: IOish m => GhcModT m a -> GhcModT (ErrorT GhcModError m) a
liftErrorT action =
GhcModT $ RWST $ \e s -> ErrorT $ Right <$> (runRWST $ unGhcModT action) e s
-- | Lift @(GhcModT IO)@ into @GhcMod@, which is an alias for @GhcModT (ErrorT
-- GhcModError IO)@.
liftGhcMod :: GhcModT IO a -> GhcMod a
liftGhcMod = liftErrorT
----------------------------------------------------------------
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
getMode :: IOish m => GhcModT m Mode
getMode = do
GhcModState mode <- get
return mode
setMode :: IOish m => Mode -> GhcModT m ()
setMode mode = put $ GhcModState mode
----------------------------------------------------------------
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 GhcModWriter 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