[Haskell-cafe] ANN: bytestring-lexing 0.3.0

wren ng thornton wren at freegeek.org
Sun Jan 29 04:11:45 CET 2012

-- bytestring-lexing 0.3.0

The bytestring-lexing package offers efficient reading and packing of 
common types like Double and Integral types.

-- Administrative Changes (since 0.2.1)

* Change of maintainer. Don Stewart handed maintainership of the package 
over to myself when I voiced interest.

* Change of repo type. The old repo for the package used Darcs-1 style 
patches. I've converted the repository to Darcs-2 hashed. This means 
that the new repository cannot exchange patches with the old Darcs-1 
repo (or any other Darcs-2 conversions that may be floating around out 
there). So anyone who's interested in contributing should scrap their 
local copies and get the new repo.

-- Code Changes (since 0.2.1)

* Added Data.ByteString.Lex.Integral which provides efficient 
implementations for reading and packing/showing integral types in 
ASCII-compatible formats including decimal, hexadecimal, and octal.

* The readDecimal function in particular has been highly optimized. The 
new version is wicked fast[1] and perfectly suitable for hot code 
locations like parsing headers for HTTP servers like Warp. In addition, 
attention has been paid to ensuring that parsing is efficient for larger 
than native types like Int64 on 32-bit systems (including 64-bit OS X), 
as well as Integer. The optimization of this function was done in 
collaboration with Erik de Castro Lopo, Vincent Hanquez, and Christoph 
Breitkopf following a blog post by Erik[2] and ensuing discussion on 

[1] A Criterion report is available for 64-bit Intel OS X running 32-bit 
GHC 6.12.1:


The benchmark is included in the repo and has also been run on 64-bit 
GHC 7 systems, which differ primarily in not showing slowdown for Int64 
vs Int (naturally). If you're curious about the different implementations:

* readIntBS / readIntegerBS --- are the readInt and readInteger 
functions in Data.ByteString

* readDecimalOrig (correct) --- was my original implementation, prior to 
collaboration with Erik, Vincent, and Christoph.

* readIntegralMH (buggy) --- or rather a non-buggy version very much 
like it, is the implementation currently used in Warp.

* readDecimal (current) --- is the current implementation used in this 

[2] http://www.mega-nerd.com/erikd/Blog/CodeHacking/Haskell/read_int.html


-- Links




Haddock (Darcs version):

Live well,

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