The io-streams library contains simple and easy to use primitives for I/O using streams. Based on simple types with one type parameter (InputStream a and OutputStream a), io-streams provides a basic interface to side-effecting input and output in IO monad with the following features:

  • three fundamental I/O primitives that anyone can understand: read :: InputStream a -> IO (Maybe a), unRead :: a -> InputStream a -> IO (), and write :: Maybe a -> OutputStream a -> IO ().

  • simple types and side-effecting IO operations mean straightforward and simple exception handling and resource cleanup using standard Haskell facilities like bracket.

  • code to transform files, handles, and sockets to streams

  • a variety of combinators for wrapping and transforming streams, including compression and decompression using zlib, controlling precisely how many bytes are read to or written from a socket, buffering output using blaze-builder, etc.

  • support for parsing from streams using attoparsec.

Changes

Version 1.5.0.1

Bugfix: concurrentMerge [] should not block forever, even if this case is pathological.

Version 1.5.0.0

  • Changed the behaviour of ByteString.splitOn to not emit empty string if the input ends in the delimiter; now lines should match Prelude's. Bumped major version because this is a potentially breaking change (even if it is a bugfix.)

Version 1.4.1.0

  • Added writeTo export to the main module (forgotten when it was added to .Core.)

Version 1.4.0.0

  • Added support for Text with Attoparsec, courtesy Kevin Brubeck Unhammer. Adds modules System.IO.Streams.Attoparsec.{ByteString, Text} and deprecates System.IO.Streams.Attoparsec, which is now a thin wrapper.

Version 1.3.6.1

  • Bumped dependencies on time and process.

Version 1.3.6.0

  • Added new fold functions:

`haskell fold_ :: (x -> a -> x) -- ^ accumulator update function -> x -- ^ initial seed -> (x -> s) -- ^ recover folded value -> InputStream a -- ^ input stream -> IO s foldM_ :: (x -> a -> IO x) -- ^ accumulator update action -> IO x -- ^ initial seed -> (x -> IO s) -- ^ recover folded value -> InputStream a -- ^ input stream -> IO s `

Version 1.3.5.0

  • Add support for latest process, time, and transformers releases (and thereby indirectly for the upcoming GHC 8.0).

Version 1.3.4.0

  • Added System.IO.Streams.Handle.handleToStreams, to conveniently create an InputStream/OutputStream pair.

Version 1.3.3.1

  • Fixed a testsuite compile error on GHC >= 7.10.

Version 1.3.3.0

  • Added a new convenience function, like chunkList but with a predicate for when to split, taking current element and current chunk length:

    ```haskell

chunkListWith :: (a -> Int -> Bool) -> InputStream a -> IO (InputStream [a]) ```

Version 1.3.2.0

  • Dependency bump for attoparsec 0.13 (another location)
  • Dependency bump for vector 0.11
  • Dependency bump for zlib 0.6

Version 1.3.1.0

  • Dependency bump for attoparsec 0.13.

Version 1.3.0.0

  • As long promised, removed the direct use of the blaze-builder package in favor of the new bytestring-builder transitional package (to be replaced by bytestring's native builder once it is mature enough).
  • Added a new convenience function, a flipped version of write:

    ```haskell

writeTo :: OutputStream a -> Maybe a -> IO () ```

Version 1.2.1.3

  • Dependency bump for primitive 0.6.

Version 1.2.1.2

  • Dependency bump for deepseq 1.4.

Version 1.2.1.1

  • Dependency bump for time 1.6.

Version 1.2.1.0

  • Added System.IO.Streams.mapMaybe for InputStream.

  • Added System.IO.Streams.contramapMaybe for OutputStream.

Version 1.2.0.1

  • System.IO.Streams.Attoparsec.parseFromStream: export more information about the context of parse errors to the message returned via ParseException.

  • Improved documentation about stream flushing in the docstring for handleToOutputStream.

Version 1.2.0.0

  • Fixed bug #27 (https://github.com/snapframework/io-streams/issues/27): makeOutputStream now properly shuts down the stream upon receiving EOF. The new invariant might break user programs if they depended on the buggy behaviour, which is the reason for the major version bump.

  • Fixed a few polymorphic bindings that started breaking in recent GHC.

  • Dependency bumps for:
    • text 1.2
    • network 2.6

Version 1.1.4.6

Moved old changelog entries to changelog.md.

Version 1.1.4.5

Allow use of attoparsec 0.12.*.

Version 1.1.4.4

Allow use of transformers 0.4.*.

Version 1.1.4.3

Allow use of new network version 2.5.

Version 1.1.4.2

Fixed a build error with network versions older than 2.4.

Version 1.1.4.1

System.IO.Streams.Network: scalability improvement: buffers for socket reads are now allocated by system malloc rather than by pinned pointers in GHC (currently pinned pointer allocation takes a global lock).

Version 1.1.4.0

Widened attoparsec and text library dependencies to allow the latest versions.

Version 1.1.3.0

Added System.IO.Streams.ByteString.takeExactly. Widened network dependency to include 2.3. Added a NoInteractiveTests flag to selectively disable some tests for environments where spawning interactive processes is impossible.

Version 1.1.2.2

Allowed newest versions of the process, test-framework, and text libraries.

Version 1.1.2.1

Fixed build error when compiled against attoparsec-0.10.0.x.

Version 1.1.2.0

Added System.IO.Streams.Concurrent.makeChanPipe, to create a simple concurrent pipe between an InputStream/OutputStream pair.

Version 1.1.1.0

Added System.IO.Streams.Network.socketToStreamsWithBufferSize, allowing control over the size of the receive buffers used when reading from sockets.

Version 1.1.0.3

Fixed an inconsistent version upper bound in the test suite.

Version 1.1.0.2

Fixed a typo in the tutorial.

Version 1.1.0.1

A couple of Haddock markup fixes.

Version 1.1.0.0

Reworked, simplified, and streamlined the internals of the library. Exports from System.IO.Streams.Internal relying on Sources and Sinks were deleted because they are no longer necessary: Source(..), Sink(..), defaultPushback, withDefaultPushback, nullSource, nullSink, singletonSource, simpleSource, sourceToStream, sinkToStream, generatorToSource, and consumerToSink.

Version 1.0.2.2

Fixed a bug in which "takeBytes 0" was erroneously requesting input from the wrapped stream.

Version 1.0.2.1

Fixed a compile error on GHC 7.0.x.

Version 1.0.2.0

Added System.IO.Streams.Process (support for communicating with system processes using streams), added new functions to System.IO.Streams.Handle for converting io-streams types to System.IO.Handles. (Now you can pass streams from this library to places that expect Handles and everything will work.)

Version 1.0.1.0

Added System.IO.Streams.Combinators.ignoreEof.

Version 1.0.0.1

Fixed some haddock markup.

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