GhcMonad

Ghc monad stuff

class (Functor m, MonadIO m, ExceptionMonad m, HasDynFlags m) => GhcMonad m where

A monad that has all the features needed by GHC API calls.

In short, a GHC monad

• allows embedding of IO actions,
• can log warnings,
• allows handling of (extensible) exceptions, and
• maintains a current session.

If you do not use Ghc or GhcT, make sure to call initGhcMonad before any call to the GHC API functions can occur.

Minimal complete definition

getSession, setSession

Methods

getSession :: m HscEnv

setSession :: HscEnv -> m ()

Instances

GhcMonad Ghc

Defined in GhcMonad

Methods

getSession :: Ghc HscEnv

setSession :: HscEnv -> Ghc ()

ExceptionMonad m => GhcMonad (GhcT m)

Defined in GhcMonad

Methods

getSession :: GhcT m HscEnv

setSession :: HscEnv -> GhcT m ()

newtype Ghc a

A minimal implementation of a GhcMonad. If you need a custom monad, e.g., to maintain additional state consider wrapping this monad or using GhcT.

Constructors

Ghc

Fields

• unGhc :: Session -> IO a

Instances

Monad Ghc

Defined in GhcMonad

Methods

(>>=) :: Ghc a -> (a -> Ghc b) -> Ghc b

(>>) :: Ghc a -> Ghc b -> Ghc b

return :: a -> Ghc a

fail :: String -> Ghc a

Functor Ghc

Defined in GhcMonad

Methods

fmap :: (a -> b) -> Ghc a -> Ghc b

(<$) :: a -> Ghc b -> Ghc a

MonadFix Ghc

Defined in GhcMonad

Methods

mfix :: (a -> Ghc a) -> Ghc a

Applicative Ghc

Defined in GhcMonad

Methods

pure :: a -> Ghc a

(<*>) :: Ghc (a -> b) -> Ghc a -> Ghc b

liftA2 :: (a -> b -> c) -> Ghc a -> Ghc b -> Ghc c

(*>) :: Ghc a -> Ghc b -> Ghc b

(<*) :: Ghc a -> Ghc b -> Ghc a

MonadIO Ghc

Defined in GhcMonad

Methods

liftIO :: IO a -> Ghc a

ExceptionMonad Ghc

Defined in GhcMonad

Methods

gcatch :: Exception e => Ghc a -> (e -> Ghc a) -> Ghc a

gmask :: ((Ghc a -> Ghc a) -> Ghc b) -> Ghc b

gbracket :: Ghc a -> (a -> Ghc b) -> (a -> Ghc c) -> Ghc c

gfinally :: Ghc a -> Ghc b -> Ghc a

HasDynFlags Ghc

Defined in GhcMonad

Methods

getDynFlags :: Ghc DynFlags

GhcMonad Ghc

Defined in GhcMonad

Methods

getSession :: Ghc HscEnv

setSession :: HscEnv -> Ghc ()

newtype GhcT m a

A monad transformer to add GHC specific features to another monad.

Note that the wrapped monad must support IO and handling of exceptions.

Constructors

GhcT

Fields

• unGhcT :: Session -> m a

Instances

Monad m => Monad (GhcT m)

Defined in GhcMonad

Methods

(>>=) :: GhcT m a -> (a -> GhcT m b) -> GhcT m b

(>>) :: GhcT m a -> GhcT m b -> GhcT m b

return :: a -> GhcT m a

fail :: String -> GhcT m a

Functor m => Functor (GhcT m)

Defined in GhcMonad

Methods

fmap :: (a -> b) -> GhcT m a -> GhcT m b

(<$) :: a -> GhcT m b -> GhcT m a

Applicative m => Applicative (GhcT m)

Defined in GhcMonad

Methods

pure :: a -> GhcT m a

(<*>) :: GhcT m (a -> b) -> GhcT m a -> GhcT m b

liftA2 :: (a -> b -> c) -> GhcT m a -> GhcT m b -> GhcT m c

(*>) :: GhcT m a -> GhcT m b -> GhcT m b

(<*) :: GhcT m a -> GhcT m b -> GhcT m a

MonadIO m => MonadIO (GhcT m)

Defined in GhcMonad

Methods

liftIO :: IO a -> GhcT m a

ExceptionMonad m => ExceptionMonad (GhcT m)

Defined in GhcMonad

Methods

gcatch :: Exception e => GhcT m a -> (e -> GhcT m a) -> GhcT m a

gmask :: ((GhcT m a -> GhcT m a) -> GhcT m b) -> GhcT m b

gbracket :: GhcT m a -> (a -> GhcT m b) -> (a -> GhcT m c) -> GhcT m c

gfinally :: GhcT m a -> GhcT m b -> GhcT m a

MonadIO m => HasDynFlags (GhcT m)

Defined in GhcMonad

Methods

getDynFlags :: GhcT m DynFlags

ExceptionMonad m => GhcMonad (GhcT m)

Defined in GhcMonad

Methods

getSession :: GhcT m HscEnv

setSession :: HscEnv -> GhcT m ()

liftGhcT :: m a -> GhcT m a

reflectGhc :: Ghc a -> Session -> IO a

Reflect a computation in the Ghc monad into the IO monad.

You can use this to call functions returning an action in the Ghc monad inside an IO action. This is needed for some (too restrictive) callback arguments of some library functions:

libFunc :: String -> (Int -> IO a) -> IO a
ghcFunc :: Int -> Ghc a

ghcFuncUsingLibFunc :: String -> Ghc a -> Ghc a
ghcFuncUsingLibFunc str =
  reifyGhc $ \s ->
    libFunc $ \i -> do
      reflectGhc (ghcFunc i) s

reifyGhc :: (Session -> IO a) -> Ghc a

getSessionDynFlags :: GhcMonad m => m DynFlags

Grabs the DynFlags from the Session

liftIO :: MonadIO m => IO a -> m a

Lift a computation from the IO monad.

data Session

The Session is a handle to the complete state of a compilation session. A compilation session consists of a set of modules constituting the current program or library, the context for interactive evaluation, and various caches.

Constructors

Session !(IORef HscEnv)

withSession :: GhcMonad m => (HscEnv -> m a) -> m a

Call the argument with the current session.

modifySession :: GhcMonad m => (HscEnv -> HscEnv) -> m ()

Set the current session to the result of applying the current session to the argument.

withTempSession :: GhcMonad m => (HscEnv -> HscEnv) -> m a -> m a

Call an action with a temporarily modified Session.

Warnings

logWarnings :: GhcMonad m => WarningMessages -> m ()

A monad that allows logging of warnings.

printException :: GhcMonad m => SourceError -> m ()

Print the error message and all warnings. Useful inside exception handlers. Clears warnings after printing.

type WarnErrLogger = forall m. GhcMonad m => Maybe SourceError -> m ()

A function called to log warnings and errors.

defaultWarnErrLogger :: WarnErrLogger