| Copyright | (c) 2019 Composewell Technologies |
|---|---|
| License | BSD3 |
| Maintainer | streamly@composewell.com |
| Stability | pre-release |
| Portability | GHC |
| Safe Haskell | Safe-Inferred |
| Language | Haskell2010 |
Streamly.FileSystem.File
Description
Warning: The API of this module is subject to change in future releases.
Especially the type for representing paths may change from FilePath to
something else.
Read and write streams and arrays to and from files specified by their paths in the file system. Unlike the handle based APIs which can have a read/write session consisting of multiple reads and writes to the handle, these APIs are one shot read or write APIs. These APIs open the file handle, perform the requested operation and close the handle. These are safer compared to the handle based APIs as there is no possibility of a file descriptor leakage.
>>>import qualified Streamly.FileSystem.File as File
Synopsis
- withFile :: (MonadIO m, MonadCatch m) => FilePath -> IOMode -> (Handle -> Stream m a) -> Stream m a
- read :: (MonadIO m, MonadCatch m) => FilePath -> Stream m Word8
- readChunksWith :: (MonadIO m, MonadCatch m) => Int -> FilePath -> Stream m (Array Word8)
- readChunks :: (MonadIO m, MonadCatch m) => FilePath -> Stream m (Array Word8)
- write :: (MonadIO m, MonadCatch m) => FilePath -> Fold m Word8 ()
- writeWith :: (MonadIO m, MonadCatch m) => Int -> FilePath -> Fold m Word8 ()
- writeChunks :: (MonadIO m, MonadCatch m) => FilePath -> Fold m (Array a) ()
Streaming IO
Stream data to or from a file or device sequentially. When reading,
the stream is lazy and generated on-demand as the consumer consumes it.
Read IO requests to the IO device are performed in chunks limited to a
maximum size of 32KiB, this is referred to as defaultChunkSize in the
documentation. One IO request may or may not read the full
chunk. If the whole stream is not consumed, it is possible that we may
read slightly more from the IO device than what the consumer needed.
Unless specified otherwise in the API, writes are collected into chunks
of defaultChunkSize before they are written to the IO device.
File IO Using Handle
withFile :: (MonadIO m, MonadCatch m) => FilePath -> IOMode -> (Handle -> Stream m a) -> Stream m a Source #
withFile name mode actopenFile and passes
the resulting handle to the computation act. The handle will be
closed on exit from withFile, whether by normal termination or by
raising an exception. If closing the handle raises an exception, then
this exception will be raised by withFile rather than any exception
raised by act.
Pre-release
Streams
read :: (MonadIO m, MonadCatch m) => FilePath -> Stream m Word8 Source #
Generate a stream of bytes from a file specified by path. The stream ends when EOF is encountered. File is locked using multiple reader and single writer locking mode.
Pre-release
readChunksWith :: (MonadIO m, MonadCatch m) => Int -> FilePath -> Stream m (Array Word8) Source #
readChunksWith size file reads a stream of arrays from file file.
The maximum size of a single array is specified by size. The actual size
read may be less than or equal to size.
Pre-release
readChunks :: (MonadIO m, MonadCatch m) => FilePath -> Stream m (Array Word8) Source #
readChunks file reads a stream of arrays from file file.
The maximum size of a single array is limited to defaultChunkSize. The
actual size read may be less than defaultChunkSize.
readChunks = readChunksWith defaultChunkSize
Pre-release
Folds
write :: (MonadIO m, MonadCatch m) => FilePath -> Fold m Word8 () Source #
Write a byte stream to a file. Accumulates the input in chunks of up to
defaultChunkSize before writing to
the IO device.
Pre-release
writeWith :: (MonadIO m, MonadCatch m) => Int -> FilePath -> Fold m Word8 () Source #
writeWith chunkSize handle writes the input stream to handle.
Bytes in the input stream are collected into a buffer until we have a chunk
of size chunkSize and then written to the IO device.
Pre-release
writeChunks :: (MonadIO m, MonadCatch m) => FilePath -> Fold m (Array a) () Source #
Write a stream of chunks to a handle. Each chunk in the stream is written to the device as a separate IO request.
Pre-release