Next PlastiCSS pin mixin

_pin.scss

@mixin pin($top: false, $right: false, $bottom: false, $left: false, $position: absolute, $all: false, $x: false, $y: false) {
  // All the same value
  @if relevant($all) {
    bottom: $all;
    left: $all;
    right: $all;
    top: $all;
  }
  @else {
    // Left == right
    @if relevant($x) {
      left: $x;
      right: $x;
    }
    // Left != right
    @else {
      @if relevant($left) {
        left: $left;
      }
      @if relevant($right) {
        right: $right;
      }
    }

    // Top == bottom
    @if relevant($y) {
      bottom: $y;
      top: $y;
    }
    @else {
      @if relevant($bottom) {
        bottom: $bottom;
      }
      @if relevant($top) {
        top: $top;
      }
    }
  }
  @if relevant($position) {
    position: $position;
  }
}

_relevant.scss

@function relevant($value, $ignore...) {
  @if length($value) == 0 or $value == false or $value == null {
    @return false;
  }

  @each $ignored in $ignore {
    @if $value == $ignored
    or  type-of($value) == color and type-of($ignored) == color and same-color($value, $ignored) {
      @return false
    }
  }

  @return true;
}

_same-color.scss

@function same-color($a, $b, $alpha: true) {
  @if $alpha and alpha($a) != alpha($b) {
    @return false;
  }

  @return rgb(red($a), green($a), blue($a)) == rgb(red($b), green($b), blue($b));
}