$positions: (
  "top-left": "0 null null 0",
  "top": "0 null null null",
  "top-right": "0 0 null null",
  "left": "null null null 0",
  "center": "50% null null 50%",
  "right": "null 0 null null",
  "bottom-left": "null null 0 0",
  "bottom": "null null 0 null",
  "bottom-right": "null 0 0 null"
);

.-abs {
  position: absolute;

  @each $position, $value in $positions {
    &.-#{$position} {
      @include position(absolute, $value);
    }
  }
}

.-rel {
  position: relative;

  @each $position, $value in $positions {
    &.-#{$position} {
      @include position(relative, $value);
    }
  }
}

.-fix {
  position: fixed;

  @each $position, $value in $positions {
    &.-#{$position} {
      @include position(fixed, $value);
    }
  }
}