Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.4)
// Compass (v1.0.1)
// ----

// LIB
// -------------------------------------------------------------------------

@function core-process-to-four-values($values) {
  $length: length($values);
  // Convert all values to 4 values
  @if $length < 4 {
    @if length($values) == 3 {
      // (T,L+R,B) We need to add the 2nd prop again as the last prop
      $values: append($values, nth($values, 2));
    } @else if $length == 2 {
      // (T+B, L+R) We need to duplicate
      $values: append($values, $values);
    } @else {
      // (T+R+B+L) We need to duplicate 4 times
      $values: append($values, $values, $values, $values);
    }
  } 
  @return $values;
}

// Process value if it isn't already a valid number
@function core-process-value($value, $orientation) {
  @if core-should-parse-value($value) {
    $value: core-parse-value-filter($value);
    $value: core-resolve-value-filter($value, $orientation);
  }
  @return $value;
}

@function core-process-values($values) {
  
  $values: core-process-to-four-properies($values);
  
  $processed-values: ();
  $orientation: vertical;
  @each $value in $values {
    @if core-should-parse-value($value) {
      $value: core-parse-value-filter($value);
      $value: core-resolve-value-filter($value, $orientation);
    }
    $processed-values: append($processed-values, $value);
  }
  @return $processed-values;
}

// 1. Check if the value maps to one of our keywords and if so, swap out the value
// This is just a hook to be overridden. By default we just pass back the value
@function core-parse-value-filter($value){
  @return $value;
}

// 2. Check if the resolved value is unitless. If so multiply the value by the rhythm
// unit we are using
// This is just a hook to be overridden. By default we just pass back the value
@function core-resolve-value-filter($value, $orientation){
  @return $value;
}

@mixin padding($value) {
  $value: core-process-values($value);
  padding: #{$value};
}

@mixin padding-top($value) {
  $value: core-process-value($value, vertical);
  padding-top: #{$value};
}

@mixin padding-right($value) {
  $value: core-process-value($value, horizontal);
  padding-right: #{$value};
}

@mixin padding-bottom($value) {
  $value: core-process-value($value, vertical);
  padding-bottom: #{$value};
}

@mixin padding-left($value) {
  $value: core-process-value($value, horizontal);
  padding-left: #{$value};
}

// UTIL
// -------------------------------------------------------------------------

$core-valid-unitless-values: "auto" "initial" "inherit" 0;

@function core-should-parse-value($value){
  @return core-is-valid-unitless($value) or core-is-number_with_unit($value);
}

@function core-is-valid-unitless($value) {
  @return not not index($core-valid-unitless-values, $value);
}

@function core-is-number_with_unit($value) {
  @return not (type-of($value) == "number" and not unitless($value));
}

// Test Defaults
// -------------------------------------------------------------------------

.Default-padding-top {
  @include padding-top(10px);
}

.Default-padding-right {
  @include padding-right(10px);
}

// APP
// -------------------------------------------------------------------------

$rhythm-units-map: (
  single: 1,
  double: 2,
  triple: 3,
  quadruple: 4,
  half: 0.5,
  third: 0.33333333333,
  quarter: 0.25
);

$rhythm-map: (
  vertical: 12px,
  horizontal: 16px
);

// If the value isn't a united number or a known keyword, look up the keyword 
// in the $rhythm-units-map (which will resolve to a unitless number)
@function core-parse-value-filter($key){
  @if map-has-key($rhythm-units-map, $key) {
    @return map-get($rhythm-units-map, $key);
  } @else {
    @error 'Unsupported key';
  }
}

// Multiply the unitless number with the appropriate rhythm-unit
// in the $rhythm-units-map (depending on vertical or horizontal orientation)
@function core-resolve-value-filter($value, $orientation){
  @return map-get($rhythm-map, $orientation) * $value;
}

// Test Custom
// -------------------------------------------------------------------------

.padding-top {
  @include padding-top(single);
}

.padding-right {
  @include padding-right(single);
}

SassMeister-output.css

.Default-padding-top {
  padding-top: 10px;
}

.Default-padding-right {
  padding-right: 10px;
}

.padding-top {
  padding-top: 12px;
}

.padding-right {
  padding-right: 16px;
}