Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.14)
// Compass (v1.0.3)
// ----

// ASSERT ------------------------------------------------------

/// Call multiple asserts at once
/// @param {*} $value
/// @param {List} $asserts
@function assert($value, $asserts) {
  @each $name, $params in $asserts {
    $value: call('assert-#{$name}', join(($value), $params)...);
  }
  
  @return $value;
}

/// Assert that $value type equal $type
/// @access public
/// @group assert
/// @param {*} $value
/// @param {String} $type
@function assert-type($value, $type) {
  @return if($type == type-of($value), $value, null);
}

/// Assert that $value is not in $excluded
/// @access public
/// @group assert
/// @param {*} $value
/// @param {*...} $excluded
@function assert-not($value, $excluded...) {
  @each $exc in $excluded {
    @if $value == $exc {
      @return null;
    }
  }
  @return $value;
}

@function assert-default($value, $default) {
  @return if(null != $value, $value, $default);
}

// DEMO --------------------------------------------------------

$foo: red;

$type:  'color';
$not:   red, green, blue;
$def:   pink;

foo {
  a: assert($foo, ());
  b: assert($foo, ('type': $type));
  c: assert($foo, ('type': $type, 'not': $not));
  d: assert($foo, ('type': $type, 'not': $not, 'default': $def));
}

SassMeister-output.css

foo {
  a: red;
  b: red;
  d: pink;
}