XProc pipeline with p:insert and language tagging.

insert-with-lang.xpl

<?xml version="1.0" encoding="UTF-8"?>
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc"
  xmlns:c="http://www.w3.org/ns/xproc-step" 
  version="1.0">
  
  <p:input port="source">
    <p:inline>
      <doc xml:lang="de-DE">
        <p>Ein deutscher Textschnipsel.</p>
      </doc>
    </p:inline>
  </p:input>
  <p:output port="result"/>
  
  <p:insert match="/doc" position="first-child">
    <p:input port="insertion" select="/doc/p">
      <p:inline>
        <doc xml:lang="en-EN">
          <p>An English text snippet.</p>
        </doc>
      </p:inline>
    </p:input>
  </p:insert>
  
</p:declare-step>