@function ballistic-replace-nth($list, $index, $value: null) {
  $result: ();

  @if type-of($index) != number {
    @return ballistic-warn("List index #{$index} is not a number for `replace-nth`/`remove-nth`.");
  }

  @else if $index == 0 {
    @return ballistic-warn("List index 0 must be a non-zero integer for `replace-nth`/`remove-nth`.");
  }

  @else if abs($index) > length($list) {
    @return ballistic-warn("List index is #{$index} but list is only #{length($list)} item long for `replace-nth`/`remove-nth`.");
  }

  @else {
    $index: if($index < 0, length($list) + $index + 1, $index);

    @for $i from 1 through length($list) {
      @if $i == $index and $value != null {
        $result: append($result, $value, comma);
      }

      @else if $i != $index {
        $result: append($result, nth($list, $i), comma);
      }
    }
  }

  @return $result;
}