RE: XML DTD for the package configuration file

15 Oct 2003

      Hi all,

Although creating package description files in XML
sounds neat, it also sounds like over-design at this
stage. Why don't we use Haskell *values* to describe
the packages? If we describe packages just like ghc-pkg
is doing, as a Haskell record, we get:

- very simple code for reading and writing those
- syntax that is understood by all haskell programmers
- optional elements (by using records)
- list elements (by using lists)

Might be not as powerful as using XML, but it might
be just right for the thing we are trying to do.

Just my 2cents,

-- Daan Leijen
...
-----Original Message-----
From: libraries-bounces@haskell.org 
[mailto:libraries-bounces@haskell.org] On Behalf Of Isaac Jones
Sent: woensdag 15 oktober 2003 6:55
To: libraries
Subject: XML DTD for the package configuration file
This is my first attempt at an XML DTD.  Does anyone have any 
suggestions for good XML references either a book or a web 
site? Google seems to be suffering from too much XML 
information.  Is there a Haddock / Javadoc type way to notate 
a DTD?  Should I be using schemas?  Are they overkill?  What 
do you think of the style? Sometimes I have trouble choosing 
between using an attribute, and using a nested element.  For instance:
<envitem><var>x</var><val>y</val></envitem>
verses
<envitem var="x">y</envitem>
Here's a shot at a DTD for the packages configuration file 
and an example config file that validates with the DTD (I 
used xmllint --noout --valid) and the Haskell datatype that 
it's meant to reflect. I expect it will change a lot as I 
learn more about XML and about packaging, but I wanted to get 
it out there in case I'm going horribly wrong somehow.
I'm not really satisfied with the version stuff or the 
versionrange stuff (mostly the Haskell code).
Slight background for people who know less about xml than me: 
a DTD is a means of verifying that an XML file has the 
correct structure.  It seems rather limited in that there are 
no types, and the regular expressions are weaker than one 
might expect (I can't say "the data in this field should 
correspond to the following regexp).  XML Schemas seem to fix 
some of these problems.  But DTDs seem to be a nice way to 
document and share information about the format of an XML file.
peace,
isaac
------------------------------------------------------------
Packages.dtd
------------------------------------------------------------
-- CUT HERE --
<!ELEMENT packageconf (package+)>
<!ATTLIST packageconf version CDATA #REQUIRED>
<!-- package -->
<!ELEMENT package 
(version?,importdirs?,sourcedirs?,librarydirs?,hslibraries?,ex
tralibraries?,depends?,builddepends?,ccopts?,ldopts?,environme
nt?,graftpoint?,extraframeworks?)>
<!ATTLIST package version CDATA #IMPLIED>
<!ATTLIST package name CDATA #REQUIRED>
<!ATTLIST package auto (false | true) "false">
<!ELEMENT packageident (#PCDATA)>
<!-- Path related -->
<!ELEMENT filepath (#PCDATA)>
<!ELEMENT sourcedirs (filepath+)>
<!ELEMENT importdirs (filepath+)>
<!ELEMENT librarydirs (filepath+)>
<!-- Libraries -->
<!ELEMENT hslibraries (library+)>
<!ELEMENT cincludes (include+)>
<!ELEMENT extralibraries (library+)>
<!ELEMENT library (#PCDATA)>
<!ELEMENT include (#PCDATA)>
<!-- Options -->
<!ELEMENT ccopts (option+)>
<!ELEMENT ldopts (option+)>
<!ELEMENT option (#PCDATA)>
<!ATTLIST option type (short | long | verbatim) "verbatim">
<!-- Depends -->
<!ELEMENT builddepends (dependency+)>
<!ELEMENT depends      (dependency+)>
<!ELEMENT dependency   (versionrange?)>
<!ATTLIST dependency name CDATA #REQUIRED>
<!ATTLIST dependency version CDATA #IMPLIED>
<!-- Documentation -->
<!ELEMENT haddockhtmlroot  (#PCDATA)>
<!ELEMENT haddockinterface (#PCDATA)>
<!-- Versioning -->
<!ELEMENT versionrange (version,version?)> <!-- second one is 
for range --> <!ATTLIST versionrange type (any | orlater | 
exactly | orearlier | between) "orlater">
<!-- I'm not exactly satisfied with this. I should also be 
able to say <= -->
<!-- and >=, but these are already pretty verbose. -->
<!ELEMENT version (numberversion | simpleversion | 
dateversion)> <!ELEMENT numberversion (major?,minor?,patch?)> 
<!ELEMENT simpleversion (#PCDATA)>
<!ELEMENT major (#PCDATA)>
<!ELEMENT minor (#PCDATA)>
<!ELEMENT patch (#PCDATA)>
<!ELEMENT dateversion (year,month?,day?,patch?)>
<!ELEMENT year  (#PCDATA)>
<!ELEMENT month (#PCDATA)>
<!ELEMENT day   (#PCDATA)>
<!-- Simpleversions should be a fixed format: 1.2.3-4 or so -->
<!-- Environment -->
<!ELEMENT environment (envitem+)>
<!ELEMENT envitem (var,val)+>
<!ELEMENT var (#PCDATA)>
<!ELEMENT val (#PCDATA)>
<!--        Or maybe this would be preferred? -->
<!--        <envitem> var="boing">boo</envitem> -->
<!-- Misc -->
<!ELEMENT graftpoint (#PCDATA)>
<!ELEMENT extraframeworks (framework+)>
<!ELEMENT framework (#PCDATA)>
-- CUT HERE --
------------------------------------------------------------
Packages.xml
------------------------------------------------------------
-- CUT HERE --
<?xml version="1.0"?>
<!DOCTYPE packageconf  SYSTEM "Packages.dtd">
<packageconf version="0.1">
  <package name="packageName" version="1.0" auto="true">
    <importdirs><filepath>/foo</filepath>
                <filepath>/foo/bar/bang</filepath></importdirs>
    <sourcedirs><filepath>/foo</filepath>
                <filepath>/foo/bar/bang</filepath></sourcedirs>
<graftpoint>System.IO</graftpoint>
  </package>
<!-- ============================== -->
  <package name="dependExample" version="3">
     <builddepends>
        <dependency name="otherPkg">
          <versionrange type="exactly">
      <version><simpleversion>3.4.5-6</simpleversion></version>
    </versionrange>
        </dependency>
<dependency name="otherPkg2">
          <versionrange type="orlater">
<version><dateversion><year>1998</year></dateversion></version>
    </versionrange>
        </dependency>
<dependency name="otherPkg3" version="2.0.0-0" />
<dependency name="otherPkg3">
          <versionrange type="between">
      <version><simpleversion>3.3</simpleversion></version>
      <version><simpleversion>3.5</simpleversion></version>
    </versionrange>
        </dependency>
</builddepends>
  </package>
<!-- ============================== -->
  <package name="optionExample">
     <version><numberedversion><major>10</major>
                               <minor>11</minor>
<patch>12</patch></numberedversion></version>
     <ccopts>
         <option type="short">b</option>
         <option type="long">foo</option>
         <option type="verbatim">--bar</option>
         <option>--bang</option>
     </ccopts>
<environment>
       <envitem><var>foo</var><val>bar</val></envitem>
       <envitem><var>bang</var><val>baz</val></envitem>
     </environment>
  </package>
</packageconf>
-- CUT HERE --
------------------------------------------------------------
Package Config data structure
------------------------------------------------------------
-- CUT HERE --
data PkgIdentifier
    = PkgIdentifier {pkgName::String, pkgVersion::Version}
{- ^Often need name and version since multiple versions of a single
    package can exist on a system. -}
data PackageConfig
   = Package {
        pkgIdent        :: PkgIdentifier,
        license         :: License,
        auto            :: Bool,
<!--         provides        :: [String], -->
<!-- {- ^A bit pie-in-the-sky; might indicate that this 
package provides -->
<!--     functionality that other packages also provide, such 
as a compiler -->
<!--     or GUI framework, and upon which other packages 
might depend. -} -->
<!--         isDefault       :: Bool, -->

<!-- think through isDefault more, maybe we actually want a 
list of defaults -->
import_dirs     :: [FilePath],
        source_dirs     :: [FilePath],
        library_dirs    :: [FilePath],
        include_dirs    :: [FilePath],
        hs_libraries    :: [String],
        extra_libraries :: [String],
        c_includes      :: [String],
        build_deps      :: [Dependency], -- build dependencies
        depends         :: [Dependency], -- use dependencies
<!--         extra_ghc_opts  :: [String], -->
        extra_cc_opts   :: [String],
        extra_ld_opts   :: [String],
        framework_dirs  :: [String],
        haddock_html_root :: String,
        haddock_interface :: String,
        default_grafting_point :: String,
-- ^Related to new packages proposal
        vars            :: [(String, String)],
-- ^Variable, value pairs, whatever author wants here
        extra_frameworks:: [String]}
data Version = DateVersion {versionYear  :: Integer,
                            versionMonth :: Month,
                            versionDay   :: Integer}
             | NumberedVersion {versionMajor      :: Integer,
                                versionMinor      :: Integer,
                                versionPatchLevel :: Integer}
data License = GPL | LGPL | BSD | {- ... | -} OtherLicense FilePath
data Dependency = Dependency String VersionRange
data VersionRange
  = AnyVersion
  | OrLaterVersion     Version
  | ExactlyThisVersion Version
  | OrEarlierVersion   Version
type PackageMap = FiniteMap PkgIdentifier PackageConfig
-- CUT HERE --
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