How to make array value with comma separated in XSLT 2.0

We have string array in XML look like:

<arr name="CategoryName">
   <str>Movies</str>
   <str>Movies</str>
   <str>Movies</str>
   <str>Movies</str>
   <str>Movies</str>
   <str>DVD</str>
   <str>By Languages</str>
   <str>By Title</str>
   <str>By Decades</str>
   <str>By Genre</str>
   <str>2000's</str>
   <str>Drama</str>
   <str>English</str>
   <str>QRST</str>
</arr>

and my output from xslt transformation look like:

<category>MoviesMoviesMoviesMoviesMoviesDVDBy LanguagesBy TitleBy DecadesBy Genre2000'sDramaEnglishQRST</category>

but i want to each element with comma separated like:

<category>Movies, Movies, Movies, Movies, Movies, DVD, By Languages, By Title, By Decades, By Genre, 2000's,Drama,English,QRST</category>

And my XSLT code look like:

<xsl:for-each select="$CategoryArray">
    <category><xsl:value-of select="concat($CategoryArray,', ')"/></category>
</xsl:for-each>

but its not working so pls give me solution for how make array value with comma separated.

thanks in advance.