| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
UnliftIO.IO
Description
Unlifted System.IO.
Since: 0.1.0.0
Synopsis
- data IOMode
- data Handle
- stdin :: Handle
- stdout :: Handle
- stderr :: Handle
- withFile :: MonadUnliftIO m => FilePath -> IOMode -> (Handle -> m a) -> m a
- withBinaryFile :: MonadUnliftIO m => FilePath -> IOMode -> (Handle -> m a) -> m a
- hClose :: MonadIO m => Handle -> m ()
- hFlush :: MonadIO m => Handle -> m ()
- hFileSize :: MonadIO m => Handle -> m Integer
- hSetFileSize :: MonadIO m => Handle -> Integer -> m ()
- hIsEOF :: MonadIO m => Handle -> m Bool
- data BufferMode
- hSetBuffering :: MonadIO m => Handle -> BufferMode -> m ()
- hGetBuffering :: MonadIO m => Handle -> m BufferMode
- hSeek :: MonadIO m => Handle -> SeekMode -> Integer -> m ()
- data SeekMode
- hTell :: MonadIO m => Handle -> m Integer
- hIsOpen :: MonadIO m => Handle -> m Bool
- hIsClosed :: MonadIO m => Handle -> m Bool
- hIsReadable :: MonadIO m => Handle -> m Bool
- hIsWritable :: MonadIO m => Handle -> m Bool
- hIsSeekable :: MonadIO m => Handle -> m Bool
- hIsTerminalDevice :: MonadIO m => Handle -> m Bool
- hSetEcho :: MonadIO m => Handle -> Bool -> m ()
- hGetEcho :: MonadIO m => Handle -> m Bool
- hWaitForInput :: MonadIO m => Handle -> Int -> m Bool
- hReady :: MonadIO m => Handle -> m Bool
- getMonotonicTime :: MonadIO m => m Double
Documentation
See openFile
Constructors
| ReadMode | |
| WriteMode | |
| AppendMode | |
| ReadWriteMode |
Haskell defines operations to read and write characters from and to files,
represented by values of type Handle. Each value of this type is a
handle: a record used by the Haskell run-time system to manage I/O
with file system objects. A handle has at least the following properties:
- whether it manages input or output or both;
- whether it is open, closed or semi-closed;
- whether the object is seekable;
- whether buffering is disabled, or enabled on a line or block basis;
- a buffer (whose length may be zero).
Most handles will also have a current I/O position indicating where the next
input or output operation will occur. A handle is readable if it
manages only input or both input and output; likewise, it is writable if
it manages only output or both input and output. A handle is open when
first allocated.
Once it is closed it can no longer be used for either input or output,
though an implementation cannot re-use its storage while references
remain to it. Handles are in the Show and Eq classes. The string
produced by showing a handle is system dependent; it should include
enough information to identify the handle for debugging. A handle is
equal according to == only to itself; no attempt
is made to compare the internal state of different handles for equality.
withFile :: MonadUnliftIO m => FilePath -> IOMode -> (Handle -> m a) -> m a Source #
Unlifted version of withFile.
Since: 0.1.0.0
withBinaryFile :: MonadUnliftIO m => FilePath -> IOMode -> (Handle -> m a) -> m a Source #
Unlifted version of withBinaryFile.
Since: 0.1.0.0
hSetFileSize :: MonadIO m => Handle -> Integer -> m () Source #
Lifted version of hSetFileSize
Since: 0.2.1.0
data BufferMode #
Three kinds of buffering are supported: line-buffering, block-buffering or no-buffering. These modes have the following effects. For output, items are written out, or flushed, from the internal buffer according to the buffer mode:
- line-buffering: the entire output buffer is flushed
whenever a newline is output, the buffer overflows,
a
hFlushis issued, or the handle is closed. - block-buffering: the entire buffer is written out whenever it
overflows, a
hFlushis issued, or the handle is closed. - no-buffering: output is written immediately, and never stored in the buffer.
An implementation is free to flush the buffer more frequently, but not less frequently, than specified above. The output buffer is emptied as soon as it has been written out.
Similarly, input occurs according to the buffer mode for the handle:
- line-buffering: when the buffer for the handle is not empty, the next item is obtained from the buffer; otherwise, when the buffer is empty, characters up to and including the next newline character are read into the buffer. No characters are available until the newline character is available or the buffer is full.
- block-buffering: when the buffer for the handle becomes empty, the next block of data is read into the buffer.
- no-buffering: the next input item is read and returned.
The
hLookAheadoperation implies that even a no-buffered handle may require a one-character buffer.
The default buffering mode when a handle is opened is implementation-dependent and may depend on the file system object which is attached to that handle. For most implementations, physical files will normally be block-buffered and terminals will normally be line-buffered.
Constructors
| NoBuffering | buffering is disabled if possible. |
| LineBuffering | line-buffering should be enabled if possible. |
| BlockBuffering (Maybe Int) | block-buffering should be enabled if possible.
The size of the buffer is |
Instances
| Eq BufferMode | Since: base-4.2.0.0 |
Defined in GHC.IO.Handle.Types | |
| Ord BufferMode | Since: base-4.2.0.0 |
Defined in GHC.IO.Handle.Types Methods compare :: BufferMode -> BufferMode -> Ordering # (<) :: BufferMode -> BufferMode -> Bool # (<=) :: BufferMode -> BufferMode -> Bool # (>) :: BufferMode -> BufferMode -> Bool # (>=) :: BufferMode -> BufferMode -> Bool # max :: BufferMode -> BufferMode -> BufferMode # min :: BufferMode -> BufferMode -> BufferMode # | |
| Read BufferMode | Since: base-4.2.0.0 |
Defined in GHC.IO.Handle.Types Methods readsPrec :: Int -> ReadS BufferMode # readList :: ReadS [BufferMode] # readPrec :: ReadPrec BufferMode # readListPrec :: ReadPrec [BufferMode] # | |
| Show BufferMode | Since: base-4.2.0.0 |
Defined in GHC.IO.Handle.Types Methods showsPrec :: Int -> BufferMode -> ShowS # show :: BufferMode -> String # showList :: [BufferMode] -> ShowS # | |
hSetBuffering :: MonadIO m => Handle -> BufferMode -> m () Source #
Lifted version of hSetBuffering
Since: 0.2.1.0
hGetBuffering :: MonadIO m => Handle -> m BufferMode Source #
Lifted version of hGetBuffering
Since: 0.2.1.0
hSeek :: MonadIO m => Handle -> SeekMode -> Integer -> m () Source #
Lifted version of hSeek
Since: 0.2.1.0
A mode that determines the effect of hSeek hdl mode i.
Constructors
| AbsoluteSeek | the position of |
| RelativeSeek | the position of |
| SeekFromEnd | the position of |
Instances
| Enum SeekMode | Since: base-4.2.0.0 |
| Eq SeekMode | Since: base-4.2.0.0 |
| Ord SeekMode | Since: base-4.2.0.0 |
Defined in GHC.IO.Device | |
| Read SeekMode | Since: base-4.2.0.0 |
| Show SeekMode | Since: base-4.2.0.0 |
| Ix SeekMode | Since: base-4.2.0.0 |
Defined in GHC.IO.Device | |
hIsReadable :: MonadIO m => Handle -> m Bool Source #
Lifted version of hIsReadable
Since: 0.2.1.0
hIsWritable :: MonadIO m => Handle -> m Bool Source #
Lifted version of hIsWritable
Since: 0.2.1.0
hIsSeekable :: MonadIO m => Handle -> m Bool Source #
Lifted version of hIsSeekable
Since: 0.2.1.0
hIsTerminalDevice :: MonadIO m => Handle -> m Bool Source #
Lifted version of hIsTerminalDevice
Since: 0.2.1.0
hWaitForInput :: MonadIO m => Handle -> Int -> m Bool Source #
Lifted version of hWaitForInput
Since: 0.2.1.0
getMonotonicTime :: MonadIO m => m Double Source #
Get the number of seconds which have passed since an arbitrary starting time, useful for calculating runtime in a program.
Since: 0.2.3.0