Control selection order from a sequence - xquery

Question

How do I control the order of selection from a for $x in (...) ? In the last line of XQuery below, I want the result to be in the order $retmax, $retmin, but it comes out in reverse order.
<result>
{
let $max := max(doc("countries.xml")//country/(#population div #area))
let $min := min(doc("countries.xml")//country/(#population div #area))
for $country in doc("countries.xml")//country
let $density := $country/(#population div #area)
let $ret_min := if ($density = $min)
then <lowest density="{$density}">{data($country/#name)}</lowest>
else ()
let $ret_max := if ($density = $max)
then <highest density="{$density}">{data($country/#name)}</highest>
else ()
for $r in ($ret_max, $ret_min) return $r
}
</result>
produces:
<result>
<lowest density="0.026752619966905682">Greenland</lowest>
<highest density="31052.3125">Macau</highest>
</result>
but I want:
<result>
<highest density="31052.3125">Macau</highest>
<lowest density="0.026752619966905682">Greenland</lowest>
</result>

Answer 1

Here's how I'd write it...
let $ordered_countries := for $country in doc("countries.xml")//country
let $density := $country/(#population div #area)
order by $density
return $country
let $low := $ordered_countries[1]
let $high := $ordered_countries[fn:last()]
return (
<lowest density="{$low/(#population div #area)}">{data($low/#name)}</lowest>,
<highest density="{$high/(#population div #area)}">{data($high/#name)}</highest>
)