typed XML in OCaml (plugins)

 TyXML allows one to build XML trees whose validity is ensured by the
 typechecker. It's based on a translation of XML types into polymorphic
 variants, originally written by Thorsten Ohl. Currently, the
 transcription has been done for XHTML 1.0 and 1.1, HTML5 and SVG
 (partial).
 .
 TyXML also provides a generic printer and some low-level (and
 untyped) iterators over XML trees. The printer has options for
 printing XHTML in more browser-friendly way when served as
 "text/html" (instead of "text/xml"). HTML5 is always printed with
 those options.
 .
 All modules provided by TyXML are also provided in functorial
 interface, where every module is parameterised by the underlying XML
 representation.
 .
 A camlp4 extension, named Pa_tyxml, allows one to write HTML pages or
 HTML fragments with the usual syntax.
 .
 This package contains dynamically loadable modules for plugins.