The Haskell XML Toolbox is a collection of tools for processing XML with Haskell. It is itself purely written in Haskell. The Haskell XML Toolbox is a project of the University of Applied Sciences Wedel, initiated by Uwe Schmidt.
The core component of the Haskell XML Toolbox is a validating XML-Parser that supports almost fully the Extensible Markup Language (XML) 1.0 (Second Edition).
The Haskell XML Toolbox bases on the ideas of HaXml and HXML, but introduces a more general approach for processing XML with Haskell. The Haskell XML Toolbox uses a generic data model for representing XML documents, including the DTD subset and the document subset, in Haskell. This data model makes it possible to use filter functions as a uniform design of XML processing applications. The whole XML parser including the validator parts was implemented using this design. Libraries with filters and combinators are provided for processing the generic data model.
An new more flexible and typesaver API based on arrows instead of filters is included since version 5.2. There is a cookbook for using this arrow interface to build (nontrivial) applications. Manuel Ohlendorf has developed examples for processing RDF and has documented the development in his master thesis: A Cookbook for the Haskell XML Toolbox with Examples for Processing RDF Documents (the thesis as PDF)
Features:
A (somewhat) gentle introduction to HXT is avalable in the Haskell Wiki.
The XSLT transformer has been developed by Tim Walkenhorst in this master thesis: Implementing an XSLT processor for the Haskell XML Toolbox. It's a rather complete implementation, but it's of course not a substitute for Xalan or other advanced XSLT systems. The XSLT module consists of less than 2000 lines of code. Compared with the more than 300,000 lines of Java for Xalan, this Haskell code can be viewed as one of the first formal specifications for XSLT.
Manuel Ohlendorfs master thesis, describing the arrow interface of the toolbox: A Cookbook for the Haskell XML Toolbox with Examples for Processing RDF Documents (the thesis as PDF). The source code of the example application is included in the doc/cookbook directory of the distribution.
The master's thesis "Design and Implementation of a validating XML parser in Haskell" by Martin Schmidt describes the design and motivation of the Haskell XML Toolbox (the thesis as HTML or PDF) and the development of the DTD validator module. The documentation in the thesis is a bit out of date, the modules and module names and some function names have been changed. For details the online haddock documentation should be used.
The description of the development of the XPath modules is described (in german) in Konzeption und Implementierung eines XPath-Moduls für die Haskell XML Toolbox (PDF-document).
The description of the internals of the Relax NG validator modules is described (in german) in Design und Entwicklung eines Relax NG Schema Validators auf Basis der Haskell XML Toolbox (PDF-document).
The Filter API Documentation generated with Haddock. For the new arrow interface there is a more user friendly Arrow API Documentation including only the basic types and the arrow descriptions.
Haskell XML Toolbox 7.4, released 2007-12-12:
hxt with Cabal or make.
This package contains a Haskell DOM, an XML parser, a
DTD validator, namespace processing functions, a Relax
NG validator, an XPath expression evaluator, an XSLT transformer,
and serialization/deserialisation of data to/from XML.
curl
The HTTP module must be installed before installing the
toolbox.
In the past the installation procedure for HTTP was a bit clumsy because of further
dependencies on The Haskell Cryptographic Library
and NewBinary package. The latest HTTP module
from 2006-07-07 has removed these dependencies and consists only of one HTTP module (not HTTP and Browser).
So there has only one package HTTP to be installed before installing HXT.
HUnitTest for testing
and demonstration of the available set of filters.
A darcs repository is available under http://darcs.fh-wedel.de/hxt.
Before installing this version, install the Haskell HTTP module. For a quick install with Cabal execute the following commands in .../HXT-7.4
make setup
./setup configure --ghc
./setup build
./setup install # with root privileges
A quick test of the example programs:
cd examples
make all
make test
Installation without Cabal with GNU make:
make all
make install # with root privileges
The parser has been tested with the XML Validation Suite form the W3C. The following problems have been encountered:
Portability to Windows based systems has not been tested very intensively, but did work on an XP system with the Cygwin tools installed. Development was done under Linux with GHC 6.4 with the -Wall flag. No warnings were issued, when compiling the toolbox sources.
Haskell Modules and Libraries used in the toolbox
We are interested in hearing your feedback
on our Haskell XML Toolbox, suggestions
for improvements, comments and criticisms.
Mail address is hxmltoolbox@fh-wedel.de
| The Haskell XML Toolbox is distributed under the MIT License. |
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| Last modified: 2007-12-12 |