IO

Documentation

putStr :: (MonadIO m, Printable p) => p -> m ()

putStrLn :: (MonadIO m, Printable p) => p -> m ()

managed :: (forall r. (a -> IO r) -> IO r) -> Managed a

Build a Managed value

data Managed a :: * -> *

A managed resource that you acquire using with

Instances

Monad Managed

Methods

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

(>>) :: Managed a -> Managed b -> Managed b

return :: a -> Managed a

fail :: String -> Managed a

Functor Managed

Methods

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

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

Applicative Managed

Methods

pure :: a -> Managed a

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

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

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

MonadIO Managed

Methods

liftIO :: IO a -> Managed a

MonadManaged Managed

Methods

using :: Managed a -> Managed a

Floating a => Floating (Managed a)

Methods

pi :: Managed a

exp :: Managed a -> Managed a

log :: Managed a -> Managed a

sqrt :: Managed a -> Managed a

(**) :: Managed a -> Managed a -> Managed a

logBase :: Managed a -> Managed a -> Managed a

sin :: Managed a -> Managed a

cos :: Managed a -> Managed a

tan :: Managed a -> Managed a

asin :: Managed a -> Managed a

acos :: Managed a -> Managed a

atan :: Managed a -> Managed a

sinh :: Managed a -> Managed a

cosh :: Managed a -> Managed a

tanh :: Managed a -> Managed a

asinh :: Managed a -> Managed a

acosh :: Managed a -> Managed a

atanh :: Managed a -> Managed a

log1p :: Managed a -> Managed a

expm1 :: Managed a -> Managed a

log1pexp :: Managed a -> Managed a

log1mexp :: Managed a -> Managed a

Fractional a => Fractional (Managed a)

Methods

(/) :: Managed a -> Managed a -> Managed a

recip :: Managed a -> Managed a

fromRational :: Rational -> Managed a

Num a => Num (Managed a)

Methods

(+) :: Managed a -> Managed a -> Managed a

(-) :: Managed a -> Managed a -> Managed a

(*) :: Managed a -> Managed a -> Managed a

negate :: Managed a -> Managed a

abs :: Managed a -> Managed a

signum :: Managed a -> Managed a

fromInteger :: Integer -> Managed a

Monoid a => Monoid (Managed a)

Methods

mempty :: Managed a

mappend :: Managed a -> Managed a -> Managed a

mconcat :: [Managed a] -> Managed a

class MonadIO m => MonadManaged m where

You can embed a Managed action within any Monad that implements MonadManaged by using the using function

All instances must obey the following two laws:

using (return x) = return x

using (m >>= f) = using m >>= \x -> using (f x)

Minimal complete definition

using

Methods

using :: Managed a -> m a

Instances

MonadManaged Managed

Methods

using :: Managed a -> Managed a

MonadManaged m => MonadManaged (MaybeT m)

Methods

using :: Managed a -> MaybeT m a

MonadManaged m => MonadManaged (IdentityT * m)

Methods

using :: Managed a -> IdentityT * m a

(Monoid w, MonadManaged m) => MonadManaged (WriterT w m)

Methods

using :: Managed a -> WriterT w m a

(Monoid w, MonadManaged m) => MonadManaged (WriterT w m)

Methods

using :: Managed a -> WriterT w m a

MonadManaged m => MonadManaged (StateT s m)

Methods

using :: Managed a -> StateT s m a

MonadManaged m => MonadManaged (StateT s m)

Methods

using :: Managed a -> StateT s m a

MonadManaged m => MonadManaged (ExceptT e m)

Methods

using :: Managed a -> ExceptT e m a

MonadManaged m => MonadManaged (ReaderT * r m)

Methods

using :: Managed a -> ReaderT * r m a

MonadManaged m => MonadManaged (ContT * r m)

Methods

using :: Managed a -> ContT * r m a

(Monoid w, MonadManaged m) => MonadManaged (RWST r w s m)

Methods

using :: Managed a -> RWST r w s m a

(Monoid w, MonadManaged m) => MonadManaged (RWST r w s m)

Methods

using :: Managed a -> RWST r w s m a

runManaged :: Managed () -> IO ()

Run a Managed computation, enforcing that no acquired resources leak

data TempFile

tfPath :: Lens' TempFile AbsFile

tfHandle :: Lens' TempFile Handle

tempFile :: AbsDir -> RelFile -> Managed TempFile

class Monad m => MonadIO m where

Monads in which IO computations may be embedded. Any monad built by applying a sequence of monad transformers to the IO monad will be an instance of this class.

Instances should satisfy the following laws, which state that liftIO is a transformer of monads:

• liftIO . return = return

• liftIO (m >>= f) = liftIO m >>= (liftIO . f)

Minimal complete definition

liftIO

Methods

liftIO :: IO a -> m a

Lift a computation from the IO monad.

Instances

MonadIO IO

Methods

liftIO :: IO a -> IO a

MonadIO Managed

Methods

liftIO :: IO a -> Managed a

MonadIO m => MonadIO (MaybeT m)

Methods

liftIO :: IO a -> MaybeT m a

MonadIO m => MonadIO (ListT m)

Methods

liftIO :: IO a -> ListT m a

MonadIO m => MonadIO (ResourceT m)

Methods

liftIO :: IO a -> ResourceT m a

MonadIO m => MonadIO (IdentityT * m)

Methods

liftIO :: IO a -> IdentityT * m a

(Monoid w, MonadIO m) => MonadIO (WriterT w m)

Methods

liftIO :: IO a -> WriterT w m a

(Monoid w, MonadIO m) => MonadIO (WriterT w m)

Methods

liftIO :: IO a -> WriterT w m a

MonadIO m => MonadIO (StateT s m)

Methods

liftIO :: IO a -> StateT s m a

MonadIO m => MonadIO (StateT s m)

Methods

liftIO :: IO a -> StateT s m a

(Error e, MonadIO m) => MonadIO (ErrorT e m)

Methods

liftIO :: IO a -> ErrorT e m a

(Functor f, MonadIO m) => MonadIO (FreeT f m)

Methods

liftIO :: IO a -> FreeT f m a

MonadIO m => MonadIO (ExceptT e m)

Methods

liftIO :: IO a -> ExceptT e m a

MonadIO m => MonadIO (ReaderT * r m)

Methods

liftIO :: IO a -> ReaderT * r m a

MonadIO m => MonadIO (ContT * r m)

Methods

liftIO :: IO a -> ContT * r m a

(Monoid w, MonadIO m) => MonadIO (RWST r w s m)

Methods

liftIO :: IO a -> RWST r w s m a

(Monoid w, MonadIO m) => MonadIO (RWST r w s m)

Methods

liftIO :: IO a -> RWST r w s m a

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

Lift a computation from the IO monad.

hSeek :: Handle -> SeekMode -> Integer -> IO ()

Computation hSeek hdl mode i sets the position of handle hdl depending on mode. The offset i is given in terms of 8-bit bytes.

If hdl is block- or line-buffered, then seeking to a position which is not in the current buffer will first cause any items in the output buffer to be written to the device, and then cause the input buffer to be discarded. Some handles may not be seekable (see hIsSeekable), or only support a subset of the possible positioning operations (for instance, it may only be possible to seek to the end of a tape, or to a positive offset from the beginning or current position). It is not possible to set a negative I/O position, or for a physical file, an I/O position beyond the current end-of-file.

This operation may fail with:

• isIllegalOperationError if the Handle is not seekable, or does not support the requested seek mode.
• isPermissionError if a system resource limit would be exceeded.

data SeekMode :: *

A mode that determines the effect of hSeek hdl mode i.

Constructors

AbsoluteSeek

the position of hdl is set to i.

RelativeSeek

the position of hdl is set to offset i from the current position.

SeekFromEnd

the position of hdl is set to offset i from the end of the file.

Instances

Enum SeekMode

Methods

succ :: SeekMode -> SeekMode

pred :: SeekMode -> SeekMode

toEnum :: Int -> SeekMode

fromEnum :: SeekMode -> Int

enumFrom :: SeekMode -> [SeekMode]

enumFromThen :: SeekMode -> SeekMode -> [SeekMode]

enumFromTo :: SeekMode -> SeekMode -> [SeekMode]

enumFromThenTo :: SeekMode -> SeekMode -> SeekMode -> [SeekMode]

Eq SeekMode

Methods

(==) :: SeekMode -> SeekMode -> Bool

(/=) :: SeekMode -> SeekMode -> Bool

Ord SeekMode

Methods

compare :: SeekMode -> SeekMode -> Ordering

(<) :: SeekMode -> SeekMode -> Bool

(<=) :: SeekMode -> SeekMode -> Bool

(>) :: SeekMode -> SeekMode -> Bool

(>=) :: SeekMode -> SeekMode -> Bool

max :: SeekMode -> SeekMode -> SeekMode

min :: SeekMode -> SeekMode -> SeekMode

Read SeekMode

Methods

readsPrec :: Int -> ReadS SeekMode

readList :: ReadS [SeekMode]

readPrec :: ReadPrec SeekMode

readListPrec :: ReadPrec [SeekMode]

Show SeekMode

Methods

showsPrec :: Int -> SeekMode -> ShowS

show :: SeekMode -> String

showList :: [SeekMode] -> ShowS

Ix SeekMode

Methods

range :: (SeekMode, SeekMode) -> [SeekMode]

index :: (SeekMode, SeekMode) -> SeekMode -> Int

unsafeIndex :: (SeekMode, SeekMode) -> SeekMode -> Int

inRange :: (SeekMode, SeekMode) -> SeekMode -> Bool

rangeSize :: (SeekMode, SeekMode) -> Int

unsafeRangeSize :: (SeekMode, SeekMode) -> Int

file :: AbsRelFile -> IOMode -> Managed Handle