Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.0.rc.2)
// Compass (v1.0.0.alpha.21)
// ----


$value-1: one;
$value-2: two;

$list-1: one two;
$list-2: three four;

$empty: ();


body {
  // combine two single values, works fine
  list-1: append($value-1, $value-2, comma);
  
  // combine two space separated lists, not works
  list-2: append($list-1, $list-2, comma);
  list-2-length: length(append($list-1, $list-2, comma));
  
  // combine an empty value and two space separated lists, works fine again
  list-3: append(append($empty, $list-1), $list-2, comma);  
  list-3-length: length(append(append($empty, $list-1), $list-2, comma));
}

SassMeister-output.css

body {
  list-1: one, two;
  list-2: one, two, three four;
  list-2-length: 3;
  list-3: one two, three four;
  list-3-length: 2;
}