Data.Conduit.Binary

Functions for interacting with bytes.

For many purposes, it's recommended to use the conduit-combinators library, which provides a more complete set of functions.

Files and Handles

Note that most of these functions live in the MonadResource monad to ensure resource finalization even in the presence of exceptions. In order to run such code, you will need to use runResourceT.

Sources

sourceFile :: MonadResource m => FilePath -> Producer m ByteString

Stream the contents of a file as binary data.

Since 0.3.0

sourceHandle :: MonadIO m => Handle -> Producer m ByteString

Stream the contents of a Handle as binary data. Note that this function will not automatically close the Handle when processing completes, since it did not acquire the Handle in the first place.

Since 0.3.0

sourceHandleUnsafe :: MonadIO m => Handle -> Source m ByteString

Same as sourceHandle, but instead of allocating a new buffer for each incoming chunk of data, reuses the same buffer. Therefore, the ByteStrings yielded by this function are not referentially transparent between two different yields.

This function will be slightly more efficient than sourceHandle by avoiding allocations and reducing garbage collections, but should only be used if you can guarantee that you do not reuse a ByteString (or any slice thereof) between two calls to await.

Since 1.0.12

sourceIOHandle :: MonadResource m => IO Handle -> Producer m ByteString

An alternative to sourceHandle. Instead of taking a pre-opened Handle, it takes an action that opens a Handle (in read mode), so that it can open it only when needed and close it as soon as possible.

Since 0.3.0

sourceFileRange

Arguments

:: MonadResource m

=> FilePath

-> Maybe Integer

Offset

-> Maybe Integer

Maximum count

-> Producer m ByteString

Stream the contents of a file as binary data, starting from a certain offset and only consuming up to a certain number of bytes.

Since 0.3.0

sourceHandleRange

Arguments

:: MonadIO m

=> Handle

-> Maybe Integer

Offset

-> Maybe Integer

Maximum count

-> Producer m ByteString

Stream the contents of a handle as binary data, starting from a certain offset and only consuming up to a certain number of bytes.

Since 1.0.8

sourceHandleRangeWithBuffer

Arguments

:: MonadIO m

=> Handle

-> Maybe Integer

Offset

-> Maybe Integer

Maximum count

-> Int

Buffer size

-> Producer m ByteString

Stream the contents of a handle as binary data, starting from a certain offset and only consuming up to a certain number of bytes. This function consumes chunks as specified by the buffer size.

Since 1.1.8

withSourceFile :: (MonadUnliftIO m, MonadIO n) => FilePath -> (ConduitM i ByteString n () -> m a) -> m a

Like withBinaryFile, but provides a source to read bytes from.

Since: 1.2.1

Sinks

sinkFile :: MonadResource m => FilePath -> Consumer ByteString m ()

Stream all incoming data to the given file.

Since 0.3.0

sinkFileCautious :: MonadResource m => FilePath -> ConduitM ByteString o m ()

Cautious version of sinkFile. The idea here is to stream the values to a temporary file in the same directory of the destination file, and only on successfully writing the entire file, moves it atomically to the destination path.

In the event of an exception occurring, the temporary file will be deleted and no move will be made. If the application shuts down without running exception handling (such as machine failure or a SIGKILL), the temporary file will remain and the destination file will be untouched.

Since: 1.1.14

sinkTempFile

Arguments

:: MonadResource m

=> FilePath

temp directory

-> String

filename pattern

-> ConduitM ByteString o m FilePath

Stream data into a temporary file in the given directory with the given filename pattern, and return the temporary filename. The temporary file will be automatically deleted when exiting the active ResourceT block, if it still exists.

Since: 1.1.15

sinkSystemTempFile

Arguments

:: MonadResource m

=> String

filename pattern

-> ConduitM ByteString o m FilePath

Same as sinkTempFile, but will use the default temp file directory for the system as the first argument.

Since: 1.1.15

sinkHandle :: MonadIO m => Handle -> Consumer ByteString m ()

Stream all incoming data to the given Handle. Note that this function will not automatically close the Handle when processing completes.

Since 0.3.0

sinkIOHandle :: MonadResource m => IO Handle -> Consumer ByteString m ()

An alternative to sinkHandle. Instead of taking a pre-opened Handle, it takes an action that opens a Handle (in write mode), so that it can open it only when needed and close it as soon as possible.

Since 0.3.0

withSinkFile :: (MonadUnliftIO m, MonadIO n) => FilePath -> (ConduitM ByteString o n () -> m a) -> m a

Like withBinaryFile, but provides a sink to write bytes to.

Since: 1.2.1

withSinkFileBuilder :: (MonadUnliftIO m, MonadIO n) => FilePath -> (ConduitM Builder o n () -> m a) -> m a

Same as withSinkFile, but lets you use a Builder.

Since: 1.2.1

Conduits

conduitFile :: MonadResource m => FilePath -> Conduit ByteString m ByteString

Stream the contents of the input to a file, and also send it along the pipeline. Similar in concept to the Unix command tee.

Since 0.3.0

conduitHandle :: MonadIO m => Handle -> Conduit ByteString m ByteString

Stream the contents of the input to a Handle, and also send it along the pipeline. Similar in concept to the Unix command tee. Like sourceHandle, does not close the handle on completion. Related to: conduitFile.

Since 1.0.9

Utilities

Sources

sourceLbs :: Monad m => ByteString -> Producer m ByteString

Stream the chunks from a lazy bytestring.

Since 0.5.0

Sinks

head :: Monad m => Consumer ByteString m (Maybe Word8)

Return the next byte from the stream, if available.

Since 0.3.0

dropWhile :: Monad m => (Word8 -> Bool) -> Consumer ByteString m ()

Ignore all bytes while the predicate returns True.

Since 0.3.0

take :: Monad m => Int -> Consumer ByteString m ByteString

Take the given number of bytes, if available.

Since 0.3.0

drop :: Monad m => Int -> Consumer ByteString m ()

Drop up to the given number of bytes.

Since 0.5.0

sinkCacheLength :: (MonadResource m1, MonadResource m2) => Sink ByteString m1 (Word64, Source m2 ByteString)

Stream the input data into a temp file and count the number of bytes present. When complete, return a new Source reading from the temp file together with the length of the input in bytes.

All resources will be cleaned up automatically.

Since 1.0.5

sinkLbs :: Monad m => Sink ByteString m ByteString

Consume a stream of input into a lazy bytestring. Note that no lazy I/O is performed, but rather all content is read into memory strictly.

Since 1.0.5

mapM_ :: Monad m => (Word8 -> m ()) -> Consumer ByteString m ()

Perform a computation on each Word8 in a stream.

Since 1.0.10

Storable

sinkStorable :: (Monad m, Storable a) => Consumer ByteString m (Maybe a)

Consume some instance of Storable from the incoming byte stream. In the event of insufficient bytes in the stream, returns a Nothing and returns all unused input as leftovers.

Since: 1.1.13

sinkStorableEx :: (MonadThrow m, Storable a) => Consumer ByteString m a

Same as sinkStorable, but throws a SinkStorableInsufficientBytes exception (via throwM) in the event of insufficient bytes. This can be more efficient to use than sinkStorable as it avoids the need to construct/deconstruct a Maybe wrapper in the success case.

Since: 1.1.13

Conduits

isolate :: Monad m => Int -> Conduit ByteString m ByteString

Ensure that only up to the given number of bytes are consumed by the inner sink. Note that this does not ensure that all of those bytes are in fact consumed.

Since 0.3.0

takeWhile :: Monad m => (Word8 -> Bool) -> Conduit ByteString m ByteString

Return all bytes while the predicate returns True.

Since 0.3.0

lines :: Monad m => Conduit ByteString m ByteString

Split the input bytes into lines. In other words, split on the LF byte (10), and strip it from the output.

Since 0.3.0