@function _partition-list($list, $function) {
  $a: ();
  $b: ();
  @each $item in $list {
    $call-result: call(get-function($function), $item);
    @if $call-result {
      $a: append($a, $item);
    } @else {
      $b: append($b, $item);
    }
  }
  @return ($a, $b);
}