true here means child::true, a reference to an element node. It's not the
boolean constant true(). Saxon will generally give you a warning about this.

You don't have an element named true, therefore child::true returns an empty
sequence, and functions like starts-with treat an empty sequence the same as
an empty string. Every string starts with the empty string, so the function
returns true - or rather, true().

Michael Kay
Saxonica

> On 12 Dec 2018, at 21:10, Bridger Dyson-Smith bdysonsmith@xxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hi all -
>
> In the process of trying to illustrate something for a coworker, I stumbled
across some behavior that has me Very Confused. I would expect the starts-with
function to return 'false' when the second argument is not a string, but the
opposite happens: it returns 'true'.
>
> Can someone please help me understand what's happening here? Is this a sort
of type casting, or something else?
>
> Thank you in advance.
> Best,
> Bridger
>
> source.xml
> ```
> <?xml version="1.0" encoding="UTF-8"?>
> <test>
>   <my-string>This Is My String</my-string>
> </test>
> ```
>
> test.xsl
> ```
> <?xml version="1.0" encoding="UTF-8"?>
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform
<http://www.w3.org/1999/XSL/Transform>"
>   xmlns:xs="http://www.w3.org/2001/XMLSchema
<http://www.w3.org/2001/XMLSchema>"
>   exclude-result-prefixes="xs"
>   version="2.0">
>
>   <xsl:output method="xml" indent="yes" encoding="UTF-8"/>
>   <xsl:template match="@*|node()">
>     <xsl:copy>
>       <xsl:apply-templates select="@*|node()"/>
>     </xsl:copy>
>   </xsl:template>
>
>   <xsl:template match="my-string">
>     <xsl:if test="starts-with(.,true)">
>       <my-string-true>
>         <xsl:value-of select="starts-with(.,true)"/>
>         <xsl:text>###</xsl:text>
>         <xsl:value-of select="starts-with(.,'no')"/>
>       </my-string-true>
>     </xsl:if>
>   </xsl:template>
> </xsl:stylesheet>
> ```
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