Generated by SassMeister.com.

SassMeister-input.scss

// ----
// libsass (v3.0.2)
// ----

$_o-fonts-families: (
	'BentonSans': (
		'variants': (
			('weight': 'lighter', 'style': 'normal'),
			('weight': 'normal',  'style': 'normal'),
			('weight': 'bold',    'style': 'normal')
		)
	),
);

@function _oFontsVariantExists($family, $weight, $style) {
	$font-properties: map-get($_o-fonts-families, $family);
	$font-variants: map-get($font-properties, variants);

	@each $variant in $font-variants {
	  $variant-weight: map-get($variant, 'weight');
	  $variant-style: map-get($variant, 'style');

		// Check if we find the corresponding weight and style in the map
		@if ($variant-weight == $weight and $variant-style == $style) {
			@return true;
		}
	}
	@return false;
}

@mixin _oFontsVariantExists($family, $weight, $style) {
	$font-properties: map-get($_o-fonts-families, $family);
	$font-variants: map-get($font-properties, variants);

	@each $variant in $font-variants {
	  $variant-weight: map-get($variant, 'weight');
	  $variant-style: map-get($variant, 'style');

		// Check if we find the corresponding weight and style in the map
		@if ($variant-weight == $weight and $variant-style == $style) {
			content: true;
		}
	}
}


el {
  /* With a function, LibSass returns false, for some reason: */
  content: _oFontsVariantExists(BentonSans, normal, normal);
  /* Using a mixin, LibSass returns true, as expected: */
  @include _oFontsVariantExists(BentonSans, normal, normal);
}

SassMeister-output.css

el {
  /* With a function, LibSass returns false, for some reason: */
  content: false;
  /* Using a mixin, LibSass returns true, as expected: */
  content: true; }