Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.5)
// Compass (v1.0.0.alpha.18)
// ----

// https://docs.google.com/spreadsheet/ccc?key=0AgFzwMiAdIOfdDdkMVhPazVjMnI4eDdtM19VUzhOSVE&usp=sharing
@function nth-side($value, $n) {
  @while length($value) < $n {
    $value: append($value, nth($value, floor((length($value) + 1)/2)));
  }
  @return nth($value, $n);
}

@function side($value, $side) {
  $_sides: top right bottom left;
  $_index: index($_sides, $side);

  @if $_index {
    @return nth-side($value, $_index);
  }

  @warn "Unknown side `#{$side}` for `side`.";
  @return null;
}

$a: 1em;
$b: 1em 2em;
$c: 1em 2em 3em;
$d: 1em 2em 3em 4em;

by-index {
  t: nth-side($a, 1);
  t: nth-side($a, 2);
  t: nth-side($a, 3);
  t: nth-side($a, 4);
  /**/
  t: nth-side($b, 1);
  t: nth-side($b, 2);
  t: nth-side($b, 3);
  t: nth-side($b, 4);
  /**/
  t: nth-side($c, 1);
  t: nth-side($c, 2);
  t: nth-side($c, 3);
  t: nth-side($c, 4);
  /**/
  t: nth-side($d, 1);
  t: nth-side($d, 2);
  t: nth-side($d, 3);
  t: nth-side($d, 4);
}

by-side {
  t: side($a, top);
  t: side($a, right);
  t: side($a, bottom);
  t: side($a, left);
  /**/
  t: side($b, top);
  t: side($b, right);
  t: side($b, bottom);
  t: side($b, left);
  /**/
  t: side($c, top);
  t: side($c, right);
  t: side($c, bottom);
  t: side($c, left);
  /**/
  t: side($d, top);
  t: side($d, right);
  t: side($d, bottom);
  t: side($d, left);
}

SassMeister-output.css

by-index {
  t: 1em;
  t: 1em;
  t: 1em;
  t: 1em;
  /**/
  t: 1em;
  t: 2em;
  t: 1em;
  t: 2em;
  /**/
  t: 1em;
  t: 2em;
  t: 3em;
  t: 2em;
  /**/
  t: 1em;
  t: 2em;
  t: 3em;
  t: 4em;
}

by-side {
  t: 1em;
  t: 1em;
  t: 1em;
  t: 1em;
  /**/
  t: 1em;
  t: 2em;
  t: 1em;
  t: 2em;
  /**/
  t: 1em;
  t: 2em;
  t: 3em;
  t: 2em;
  /**/
  t: 1em;
  t: 2em;
  t: 3em;
  t: 4em;
}