NAME

       DtdToHaskell - a XML DTD to Haskell translator

SYNOPSIS

       DtdToHaskell [ dtdfile [ outfile ]]

       Missing file arguments or dashes (-) indicate standard input or output respectively.

DESCRIPTION

       DtdToHaskell  is a tool for translating any valid XML DTD into equivalent Haskell types.  This allows you
       to generate, edit, and transform documents as normal typed values in programs, and to read and write them
       as human-readable XML documents.  It uses the Text.XML.HaXml.XmlContent class as a framework for printing
       and parsing.

       DtdToHaskell reads and parses a DTD from dtdfile (which may be either just a DTD, or a full XML  document
       containing  an internal DTD).  It generates into outfile a Haskell module containing a collection of type
       definitions plus some class instance declarations for I/O.

       In  order  to  use  the   resulting   module,   you   need   to   import   it,   and   also   to   import
       Text.XML.HaXml.XmlContent.   To read and write XML files as values of the declared types, use some of the
       convenience functions from XmlContent.

       You will need to study the automatically-generated type declarations to write your own code using them  -
       but most things have pretty obvious parallels to the DTD structure.

LIMITATIONS

       The generated Haskell contains references to types like OneOf3 where there is a choice between n (in this
       case 3) different tags.  Currently, the module Text.XML.HaXml.OneOfN defines these types up to n=20.   If
       your  DTD requires larger choices, then use the tool MkOneOf to generate the extra size or range of sizes
       you need.

       We mangle tag names and attribute names to ensure that they have the correct lexical form in Haskell, but
       this  means  that (for instance) we can't distinguish Myname and myname, which are different names in XML
       but translate to overlapping types in Haskell (and hence probably won't compile).

       Attribute names translate into named fields: but because Haskell doesn't allow different  types  to  have
       the  same  named  field,  this means your XML document which uses the same name for similar attributes on
       different tags would crash and burn.  We have fixed this by incorporating  the  tagname  into  the  named
       field in addition to the attribute name, e.g. tagAttr instead of just attr.  Uglier, but more portable.

       XML  namespaces.   Currently,  we  just  mangle the namespace identifier into any tag name which uses it.
       Probably the right way to do it is to regard the namespace as  a  separate  imported  module,  and  hence
       translate  the  namespace  prefix  into  a  module  qualifier.   Does  this sound about right?  (It isn't
       implemented yet.)

       External subset.  Since HaXml release 1.00, we support the XML DTD external subset.  This  means  we  can
       read  and  parse  a  whole  bunch  of  files  as  part of the same DTD, and we respect INCLUDE and IGNORE
       conditional sections.  The sub-DTD files must be available locally - we don't go looking for them on  the
       web.

       There  are  some  fringe  parts  of  the  DTD we are not entirely sure about, such as Tokenised Types and
       Notation Types.  In particular, there is no validity checking of these external references.  If you  find
       a problem, mail us:
            Malcolm.Wallace@cs.york.ac.uk

COPYRIGHT

       The HaXml library and tools were written by and are copyright to
              Copyright © 1998 – 2006    Malcolm Wallace and Colin Runciman

       The library incorporates the module Text.ParserCombinators.HuttonMeijerWallace
              Copyright © 1996           Graham Hutton and Erik Meijer

       with modifications
              Copyright © 1998 – 2000    Malcolm Wallace

       and may also use or incorporate the module Text.PrettyPrint.HughesPJ
              Copyright © 1996 – 1997    John Hughes and Simon Peyton Jones

       The  HaXml  library is licensed under the terms of the GNU Lesser General Public Licence (LGPL), with the
       following special exception:

              As a relaxation of clause 6 of the LGPL, the copyright holders of this library give permission  to
              use,  copy, link, modify, and distribute, binary-only object-code versions of an executable linked
              with the Library, without requiring the supply of any mechanism to modify or replace  the  Library
              and  relink  (clauses  6a,  6b,  6c,  6d,  6e),  provided that all the other terms of clause 6 are
              complied with.

       The HaXml tools Xtract, Validate, DtdToHaskell, and MkOneOf, are licensed under  the  terms  of  the  GNU
       General Public Licence (GPL).

       This  library  and  toolset  is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
       without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.   See  the  GNU
       Licences for more details.

SEE ALSO

       MkOneOf(1), Validate(1)

AUTHOR

       This  contents  of  this  manual page was copied from the HTML documentation and slightly edited by Arjan
       Oosting <arjan@debian.org> for the Debian system (but may be used by others).