[Ur] Howto make urweb generate invalid XHTML code?

[Marc Weber]

Embed the result of this function into your xml. Eg

fun lis lis =
  <xml>
    <ul id="otnh">
      { List.mapX (fn (i) => <xml><li>{[i]}</li></xml>) lis }
    </ul>
  </xml>

embed this xml into your main xml code:

  <xml>
        {lis (Nil: list int)}<br/>
  </xml>


Eg try this validator:

http://validator.w3.org/check?uri=http%3A%2F%2Fmawercer.de%2F%7Emarc%2Ftest.html&charset=%28detect+automatically%29&doctype=Inline&group=0

(The html file was generated and uploaded to my server previously)

What's the issue?

<ul></ul>

without <li> tags is not allowed according to XHTML.
 
I agree that its very hard / impossible to check. Eg this would require
special list types which ensure having at least one element or
generating different HTML eg

0 elements:
  <ul>
    <li>no elements</li>
  </ul>

vs 1+ elements:

  <ul>
    <li>first element</li>
  </ul>


Without such different handling for the empty list case you end up
trying to proof this case:

  items <- queryCol (a sql query);
  return <xml>
    {lis items}
  </xml>

whose validness depends on the state of the database.

I don't want to blame ur. I'm glad that it makes an exception.

Anyway I think the manual should tell about such corner cases. ur/web
should be honest to its users if possible. A footnote would be good
enough.

So I don't consider this a being a bug of Ur - but of its documentation.

How do you think about this?

Marc Weber