gistfile1.txt

body common control
{
        bundlesequence => {
                "main",
        };
}

bundle agent main
{
   vars:
      "a[0][class]"   string => "any";
      "a[0][command]" string => "/bin/true";
      "a[1][class]"   string => "linux";
      "a[1][command]" string => "/bin/false";

      "m" data => mergedata( a );

      "i" slist => getindices( m );

   reports:
      "i       => [${i}]";
      "class   => ${m[${i}][class]}";
      "command => ${m[${i}][command]}";
}

neil@ettin ~/.cfagent/inputs $ cf-agent -Kf ./merge.cf 
R: class   => ${cf_null}
R: command => ${cf_null}