Data.Conduit.Zlib

Streaming compression and decompression using conduits.

Parts of this code were taken from zlib-enum and adapted for conduits.

Conduits

compress

Arguments

:: (MonadBase base m, PrimMonad base, MonadThrow m)

=> Int

Compression level

-> WindowBits

Zlib parameter (see the zlib-bindings package as well as the zlib C library)

-> Conduit ByteString m ByteString

Compress (deflate) a stream of ByteStrings. The WindowBits also control the format (zlib vs. gzip).

decompress

Arguments

:: (MonadBase base m, PrimMonad base, MonadThrow m)

=> WindowBits

Zlib parameter (see the zlib-bindings package as well as the zlib C library)

-> Conduit ByteString m ByteString

Decompress (inflate) a stream of ByteStrings. For example:

   sourceFile "test.z" $= decompress defaultWindowBits $$ sinkFile "test"

gzip :: (MonadThrow m, MonadBase base m, PrimMonad base) => Conduit ByteString m ByteString

Gzip compression with default parameters.

ungzip :: (MonadBase base m, PrimMonad base, MonadThrow m) => Conduit ByteString m ByteString

Gzip decompression with default parameters.

Flushing

compressFlush

Arguments

:: (MonadBase base m, PrimMonad base, MonadThrow m)

=> Int

Compression level

-> WindowBits

Zlib parameter (see the zlib-bindings package as well as the zlib C library)

-> Conduit (Flush ByteString) m (Flush ByteString)

Same as compress, but allows you to explicitly flush the stream.

decompressFlush

Arguments

:: (MonadBase base m, PrimMonad base, MonadThrow m)

=> WindowBits

Zlib parameter (see the zlib-bindings package as well as the zlib C library)

-> Conduit (Flush ByteString) m (Flush ByteString)

Same as decompress, but allows you to explicitly flush the stream.

Decompression combinators

multiple :: Monad m => Conduit ByteString m a -> Conduit ByteString m a

The standard decompress and ungzip functions will only decompress a single compressed entity from the stream. This combinator will exhaust the stream completely of all individual compressed entities. This is useful for cases where you have a concatenated archive, e.g. cat file1.gz file2.gz > combined.gz.

Usage:

sourceFile "combined.gz" $$ multiple ungzip =$ consume

This combinator will not fail on an empty stream. If you want to ensure that at least one compressed entity in the stream exists, consider a usage such as:

sourceFile "combined.gz" $$ (ungzip >> multiple ungzip) =$ consume

Since: 1.1.10

Re-exported from zlib-bindings

data WindowBits :: *

This specifies the size of the compression window. Larger values of this parameter result in better compression at the expense of higher memory usage.

The compression window size is the value of the the window bits raised to the power 2. The window bits must be in the range 8..15 which corresponds to compression window sizes of 256b to 32Kb. The default is 15 which is also the maximum size.

The total amount of memory used depends on the window bits and the MemoryLevel. See the MemoryLevel for the details.

Constructors

WindowBits Int

Instances

Eq WindowBits

Methods

(==) :: WindowBits -> WindowBits -> Bool

(/=) :: WindowBits -> WindowBits -> Bool

Ord WindowBits

Methods

compare :: WindowBits -> WindowBits -> Ordering

(<) :: WindowBits -> WindowBits -> Bool

(<=) :: WindowBits -> WindowBits -> Bool

(>) :: WindowBits -> WindowBits -> Bool

(>=) :: WindowBits -> WindowBits -> Bool

max :: WindowBits -> WindowBits -> WindowBits

min :: WindowBits -> WindowBits -> WindowBits

Show WindowBits

Methods

showsPrec :: Int -> WindowBits -> ShowS

show :: WindowBits -> String

showList :: [WindowBits] -> ShowS

Generic WindowBits

Associated Types

type Rep WindowBits :: * -> *

Methods

from :: WindowBits -> Rep WindowBits x

to :: Rep WindowBits x -> WindowBits

type Rep WindowBits

type Rep WindowBits = D1 (MetaData "WindowBits" "Codec.Compression.Zlib.Stream" "zlib-0.6.1.2-3sjfdoEPlrt37YiyVABDl7" False) ((:+:) (C1 (MetaCons "WindowBits" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Int))) (C1 (MetaCons "DefaultWindowBits" PrefixI False) U1))

defaultWindowBits :: WindowBits

The default WindowBits is 15 which is also the maximum size.