#include <dpl.pro>

function qsort(s) {
    return
	if #s < 2 then
	   s
	else
	let
	  p = s[1],
	  l = [e in s | e < p : e],
	  m = [e in s | e == p : e],
	  h = [e in s | e > p : e],
	  t = [q in [l, h]: qsort(q)]
	in
	  t[1] ++ m ++ t[2];
}

A = qsort([10, 9..1]);
show_p(A);