Re: Must variables that contain maps be typed?

I think this "wrapping in a document node in the absence of an as 
attribute" is explained in the note after 
https://www.w3.org/TR/xslt-30/#dt-immediate-result

Regardless of the current example of a map, where wrapping in a document 
node is almost never wanted, it is important to explain the difference 
between sequence constructors with or without as attribute to novices 
and sometimes also to more experienced users:

<xsl:variable name="foo">
   <bar/>
</xsl:variable>

$foo/bar -> <bar/>

<xsl:variable name="foo" as="element(bar)>
   <bar/>
</xsl:variable>

$foo/bar -> ()
$foo/self::bar -> <bar/>

The failure to understand this difference leads many desperate XSLT 
developers to use $foo//bar without ever knowing whether (which) one of 
the single-slash variants would have worked, too.

And then try to explain to them that // is actually a shorthand for 
/descendant-or-self::node()/ ...
(https://www.w3.org/TR/xpath-31/#abbrev)

At least I find it comforting to know that XPath/XQuery/XSLT processors 
don't process input or stylesheets nilly-willy, and that it usually pays 
to know the exact rules, even though trying to look them up in a 
plethora of specifcations can be daunting.

Gerrit

On 17.08.2020 17:57, Michael Kay wrote:
>>
>> i thought the general rule was that it was never mandatory to specify 
>> a type.
>>
> 
> Specifying a type on a variable that contains a sequence constructor 
> suppresses the default action of constructing a document node.
> 
> If the xsl:variable contains a sequence constructor that delivers a map, 
> it is never appropriate to wrap this in a document node, so the "as" 
> attribute is effectively mandatory.
> 
> Michael Kay
> Saxonica
> 
> 


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