Hhp.Ghc

The Happy Haskell Programming library. API for interactive processes

Converting the Ghc monad to the IO monad

withGHC

Arguments

:: FilePath

A target file displayed in an error message.

-> Ghc a

Ghc actions created by the Ghc utilities.

-> IO a

Converting the Ghc monad to the IO monad.

withGHC' :: Ghc a -> IO a

Initializing DynFlags

initializeFlagsWithCradle :: Options -> Cradle -> Ghc ()

Initialize the DynFlags relating to the compilation of a single file or GHC session according to the Cradle and Options provided.

Ghc utilities

boot :: Options -> Ghc String

Printing necessary information for front-end booting.

browse

Arguments

:: Options

-> ModuleString

A module name. (e.g. "Data.List")

-> Ghc String

Getting functions, classes, etc from a module. If detailed is True, their types are also obtained. If operators is True, operators are also returned.

check

Arguments

:: Options

-> [FilePath]

The target files.

-> Ghc (Either String String)

Checking syntax of a target file using GHC. Warnings and errors are returned.

info

Arguments

:: Options

-> FilePath

A target file.

-> Expression

A Haskell expression.

-> Ghc String

Obtaining information of a target expression. (GHCi's info:)

types

Arguments

:: Options

-> FilePath

A target file.

-> Int

Line number.

-> Int

Column number.

-> Ghc String

Obtaining type of a target expression. (GHCi's type:)

modules :: Options -> Ghc String

Listing installed modules.

SymMdlDb

type Symbol = String

Type of key for SymMdlDb.

data SymMdlDb

Database from Symbol to modules.

getSymMdlDb :: Ghc SymMdlDb

Creating SymMdlDb.

lookupSym :: Options -> Symbol -> SymMdlDb -> String

Looking up SymMdlDb with Symbol to find modules.

Misc

getSystemLibDir :: IO (Maybe FilePath)

Obtaining the directory for system libraries.

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

Lift a computation from the IO monad. This allows us to run IO computations in any monadic stack, so long as it supports these kinds of operations (i.e. IO is the base monad for the stack).

Example

import Control.Monad.Trans.State -- from the "transformers" library

printState :: Show s => StateT s IO ()
printState = do
  state <- get
  liftIO $ print state

Had we omitted liftIO, we would have ended up with this error:

• Couldn't match type ‘IO’ with ‘StateT s IO’
 Expected type: StateT s IO ()
   Actual type: IO ()

The important part here is the mismatch between StateT s IO () and IO ().

Luckily, we know of a function that takes an IO a and returns an (m a): liftIO, enabling us to run the program and see the expected results:

> evalStateT printState "hello"
"hello"

> evalStateT printState 3
3

runGhc

Arguments

:: Maybe FilePath

See argument to initGhcMonad.

-> Ghc a

The action to perform.

-> IO a

Run function for the Ghc monad.

It initialises the GHC session and warnings via initGhcMonad. Each call to this function will create a new session which should not be shared among several threads.

Any errors not handled inside the Ghc action are propagated as IO exceptions.

getMainFileToBeDeleted :: FilePath -> Ghc (Maybe FilePath)

data 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.

Instances

MonadFix Ghc

Defined in GHC.Driver.Monad

Methods

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

MonadIO Ghc

Defined in GHC.Driver.Monad

Methods

liftIO :: IO a -> Ghc a

Alternative Ghc

Defined in Hhp.Types

Methods

empty :: Ghc a

(<|>) :: Ghc a -> Ghc a -> Ghc a

some :: Ghc a -> Ghc [a]

many :: Ghc a -> Ghc [a]

Applicative Ghc

Defined in GHC.Driver.Monad

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

Functor Ghc

Defined in GHC.Driver.Monad

Methods

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

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

Monad Ghc

Defined in GHC.Driver.Monad

Methods

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

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

return :: a -> Ghc a

MonadCatch Ghc

Defined in GHC.Driver.Monad

Methods

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

MonadMask Ghc

Defined in GHC.Driver.Monad

Methods

mask :: ((forall a. Ghc a -> Ghc a) -> Ghc b) -> Ghc b

uninterruptibleMask :: ((forall a. Ghc a -> Ghc a) -> Ghc b) -> Ghc b

generalBracket :: Ghc a -> (a -> ExitCase b -> Ghc c) -> (a -> Ghc b) -> Ghc (b, c)

MonadThrow Ghc

Defined in GHC.Driver.Monad

Methods

throwM :: Exception e => e -> Ghc a

GhcMonad Ghc

Defined in GHC.Driver.Monad

Methods

getSession :: Ghc HscEnv

setSession :: HscEnv -> Ghc ()

HasDynFlags Ghc

Defined in GHC.Driver.Monad

Methods

getDynFlags :: Ghc DynFlags

HasLogger Ghc

Defined in GHC.Driver.Monad

Methods

getLogger :: Ghc Logger