>> Since xml->sxml accepts a namespace alist I suppose it would make sense
>> to extend sxml->xml to do the same.

Attached is a minimal patch to extend "sxml->xml" such that it accepts an
optional keyword argument "namespaces" with an alist of prefixes to
URLs, analogous to "xml->sxml".

When the namespaces alist is provided, "xmlns:prefix=url" attributes are
prepended to the element's list of attributes.


    ;; Define SVG document with namespaces
    (define the-svg "<svg xmlns='http://www.w3.org/2000/svg'
       xmlns:xlink='http://www.w3.org/1999/xlink'>
    <rect x='5' y='5' width='20' height='20'
          stroke-width='2' stroke='purple' fill='yellow'
          id='rect1' />
    <rect x='30' y='5' width='20' height='20'
          ry='5' rx='8' stroke-width='2' stroke='purple' fill='blue'
          xlink:href='#rect1' />
    </svg>")

    ;; Define alist of namespaces
    (define ns '((svg . "http://www.w3.org/2000/svg")
                 (xlink . "http://www.w3.org/1999/xlink")))

    ;; Convert to SXML, abbreviate namespaces according to ns alist
    (define the-sxml (xml->sxml the-svg #:namespaces ns))

    ;; Convert back to XML
    (sxml->xml the-sxml #:namespaces ns)

    => <svg:svg xmlns:svg="http://www.w3.org/2000/svg"
                xmlns:xlink="http://www.w3.org/1999/xlink">
         <svg:rect y="5" x="5"
                   width="20"
                   stroke-width="2"
                   stroke="purple"
                   id="rect1"
                   height="20"
                   fill="yellow" />
         <svg:rect xlink:href="#rect1"
                   y="5" x="30"
                   width="20"
                   stroke-width="2"
                   stroke="purple"
                   ry="5" rx="8"
                   height="20"
                   fill="blue" />
       </svg:svg>

Does this do what you want?

~~ Ricardo