[Haskell-cafe] ANNOUNCE: zlib and bzlib 0.4 releases

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Tue Oct 23 10:25:45 EDT 2007

I'm pleased to announce updates to the zlib and bzlib packages.

The releases are on hackage:


What's new in these releases is that the packages work with a wider
range of systems and versions of dependent packages.

In particular:
      * Works "out of the box" on Windows
                It uses a bundled copy of the zlib C library (version
                1.2.3) on Windows and uses the system zlib on all other
      * Works with ghc-6.4, 6.6, 6.8
      * Works with new bytestring versions
      * Works with older versions of zlib (eg zlib 1.1 on MacOS X)

They require Cabal-1.2.1 (which is also available on hackage and works
with all ghc versions).

The zlib and bzlib packages provide functions for compression and
decompression in the gzip and bzip2 formats. Both provide pure functions
on streams of data represented by lazy ByteStrings:

compress, decompress :: ByteString -> ByteString

This makes it easy to use either in memory or with disk or network IO.
For example a simple gzip compression program is just:

> import qualified Data.ByteString.Lazy as ByteString
> import qualified Codec.Compression.GZip as GZip
> main = ByteString.interact GZip.compress

Or you could lazily read in and decompress .gz file using:

> content <- fmap GZip.decompress (ByteString.readFile file)

Both packages are bindings to the corresponding C libs, so they depend
on those C libraries. Fortunately both zlib and bzlib2 are available on
every OS. It also means that the compression speed is as you would
expect since it's the C lib that is doing all the work.

The zlib package is now being used in cabal-install to work with .tar.gz
files. So it has actually been tested on Windows.

The development versions have new homes on code.haskell.org.

I'm very happy to get feedback on the API, the documentation or of
course any bug reports.


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