[Haskell-cafe] ANNOUNCE: binary: high performance, pure binary serialisation

[Bjorn Bringert]

On Jan 29, 2007, at 16:38 , Ross Paterson wrote:

> On Fri, Jan 26, 2007 at 01:51:01PM +1100, Donald Bruce Stewart wrote:
>>
>>         Binary: high performance, pure binary serialisation for  
>> Haskell
>>       
>> --------------------------------------------------------------------- 
>> -
>>
>> The Binary Strike Team is pleased to announce the release of a new,
>> pure, efficient binary serialisation library for Haskell, now  
>> available
>> from Hackage:
>>
>>  tarball:    http://hackage.haskell.org/cgi-bin/hackage-scripts/ 
>> package/binary/0.2
>>  darcs:      darcs get http://darcs.haskell.org/binary
>>  haddocks:   http://www.cse.unsw.edu.au/~dons/binary/Data-Binary.html
>
> Remind me again: why do you need a Put monad, which always seems to  
> have
> the argument type ()?  Monoids really are underappreciated.

I don't know if that's the main reason, but monads give you do- 
notation, which can be very nice when you are doing a long sequence  
of puts. Here's an example from the tar package [1]:

putHeaderNoChkSum :: TarHeader -> Put
putHeaderNoChkSum hdr =
     do let (filePrefix, fileSuffix) = splitLongPath 100 (tarFileName  
hdr)
        putString  100 $ fileSuffix
        putOct       8 $ tarFileMode hdr
        putOct       8 $ tarOwnerID hdr
        putOct       8 $ tarGroupID hdr
        putOct      12 $ tarFileSize hdr
        putOct      12 $ let TOD s _ = tarModTime hdr in s
        fill         8 $ ' ' -- dummy checksum
        putTarFileType $ tarFileType hdr
        putString  100 $ tarLinkTarget hdr -- FIXME: take suffix  
split at / if too long
        putString    6 $ "ustar "
        putString    2 $ " " -- strange ustar version
        putString   32 $ tarOwnerName hdr
        putString   32 $ tarGroupName hdr
        putOct       8 $ tarDeviceMajor hdr
        putOct       8 $ tarDeviceMinor hdr
        putString  155 $ filePrefix
        fill        12 $ '\NUL'

I guess mconcat [putX, putY, ... ] would work too, but the syntax is  
not quite as nice.

/Björn

[1] http://www.cs.chalmers.se/~bringert/darcs/tar/