Spacing for styles

_spacing.scss

@mixin spacing($prop: padding, $dir: top, $value: 1) {
  #{$prop}-#{$dir}: $value;
}

@function initial($string) {
  @return str-slice($string, 0, 1);
}

$properties: (
  margin,
  padding
);

$sizes: (
  0: 0px,
  1: 3px,
  2: 5px,
  3: 7px,
  4: 10px,
  5: 15px,
  6: 25px,
  7: 50px
);

$positions: (
  top,
  right,
  bottom,
  left
);

$elements: (
  h1,
  h2,
  h3,
  h4,
  h5,
  h6,
  p,
  li,
  i,
  a,
  small,
  ul,
  ol,
  form,
  input,
  button,
  null
);

@each $element in $elements {
  @each $prop in $properties {
    @each $position in $positions {
      @each $size_name, $size_value in $sizes {
        #{$element}.#{initial($prop)}#{initial($position)}-#{$size_name} {
          @include spacing($prop, $position, $size_value);
        }
      }
    }
  }
}

Generates spacing classes for margin and padding.

.pl-5 {
  padding-left: 15px;
}

.mt-0 {
  margin-top: 0px;
}