Copyright | © 2016 All rights reserved. |
---|---|
License | GPL-3 |
Maintainer | Evan Cofsky <evan@theunixman.com> |
Stability | experimental |
Portability | POSIX |
Safe Haskell | None |
Language | Haskell2010 |
- putStr :: (MonadIO m, Printable p) => p -> m ()
- putStrLn :: (MonadIO m, Printable p) => p -> m ()
- managed :: (forall r. (a -> IO r) -> IO r) -> Managed a
- data Managed a :: * -> *
- class MonadIO m => MonadManaged m where
- runManaged :: Managed () -> IO ()
- data TempFile
- tfPath :: Lens' TempFile AbsFile
- tfHandle :: Lens' TempFile Handle
- tempFile :: AbsDir -> RelFile -> Managed TempFile
- class Monad m => MonadIO m where
- liftIO :: MonadIO m => forall a. IO a -> m a
- hSeek :: Handle -> SeekMode -> Integer -> IO ()
- data SeekMode :: *
Documentation
class MonadIO m => MonadManaged m where #
MonadManaged Managed | |
MonadManaged m => MonadManaged (MaybeT m) | |
(Monoid w, MonadManaged m) => MonadManaged (WriterT w m) | |
(Monoid w, MonadManaged m) => MonadManaged (WriterT w m) | |
MonadManaged m => MonadManaged (StateT s m) | |
MonadManaged m => MonadManaged (StateT s m) | |
MonadManaged m => MonadManaged (IdentityT * m) | |
MonadManaged m => MonadManaged (ExceptT e m) | |
MonadManaged m => MonadManaged (ReaderT * r m) | |
MonadManaged m => MonadManaged (ContT * r m) | |
(Monoid w, MonadManaged m) => MonadManaged (RWST r w s m) | |
(Monoid w, MonadManaged m) => MonadManaged (RWST r w s m) | |
runManaged :: Managed () -> IO () #
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:
MonadIO IO | |
MonadIO Managed | |
MonadIO m => MonadIO (MaybeT m) | |
MonadIO m => MonadIO (ListT m) | |
MonadIO m => MonadIO (ResourceT m) | |
(Monoid w, MonadIO m) => MonadIO (WriterT w m) | |
(Monoid w, MonadIO m) => MonadIO (WriterT w m) | |
MonadIO m => MonadIO (StateT s m) | |
MonadIO m => MonadIO (StateT s m) | |
MonadIO m => MonadIO (IdentityT * m) | |
(Error e, MonadIO m) => MonadIO (ErrorT e m) | |
MonadIO m => MonadIO (ExceptT e m) | |
(Functor f, MonadIO m) => MonadIO (FreeT f m) | |
MonadIO m => MonadIO (ReaderT * r m) | |
MonadIO m => MonadIO (ContT * r m) | |
(Monoid w, MonadIO m) => MonadIO (RWST r w s m) | |
(Monoid w, MonadIO m) => MonadIO (RWST r w s m) | |
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.
A mode that determines the effect of hSeek
hdl mode i
.
AbsoluteSeek | the position of |
RelativeSeek | the position of |
SeekFromEnd | the position of |