CSS horizontal/vertical unit parser (for horizontal/vertical rhythm)

SassMeister-input.scss

// ----
// Sass (v3.3.9)
// Compass (v1.0.0.alpha.20)
// By @ourmaninamsterdam
// ----

@function px-to-rem($px){
  @return ( $px / $base-font-size ) * 1rem;
}

$base-font-size: 16;
$v-unit: px-to-rem(6);
$h-unit: px-to-rem(10);

@function units($args){
  @if length($args) > 4 {
    @warn "Too many arguments passed";
    @return null;
  }
  $values: ();
  @for $i from 1 through length($args){
    $arg: nth($args,$i) * if($i % 2 == 0, $h-unit, $v-unit);
    $values: append($values, $arg);
  }
  @return $values;
}

@function u($args...){
  @return units($args...);
}

.example {
  padding: u(1);
  padding: u(1 2);
  padding: u(1 2 3);
  padding: u(1 2 3 4);
  padding: u(1) 56px u(5);
  padding: 215px 100px u(5/2) 3px;
}

SassMeister-output.css

.example {
  padding: 0.375rem;
  padding: 0.375rem 1rem;
  padding: 0.375rem 1rem 1.125rem;
  padding: 0.375rem 1rem 1.125rem 2rem;
  padding: 0.375rem 56px 1.875rem;
  padding: 215px 100px 0.9375rem 3px;
}