Using SGML/XML in literate code

[Peter Simons]

I understand that I can mark-up code segments in a literate source
module using the syntax:

    \begin{code}
    ...
    \end{code}

But is it somehow possible to re-define this to be

    <haskellcode>
    ...
    </haskellcode>

instead? I am asking because the latter style would enable me to write
literate programs in DocBook, HTML, or any other SGML-based mark-up
format. And _that_ would be very useful indeed. :-)

        -peter