Font specs in Sass using maps

input.scss

// ----
// Sass (v3.3.10)
// Compass (v1.0.0.alpha.20)
// ----


// ----------------------
// HELPER FUNCTIONS HERE
// ----------------------
@function size($multiplier) {
  @return map-get($base, font-size) * $multiplier;
}

@function line-height($size) {
  @return $size * map-get($base, base-multiplier);
}

@function font-family($name) {
  $desiredFont:  map-get(map-get($font-families, $name), name);
  $fallbackFont: map-get(map-get($font-families, $name), fallback);
  @return #{ $desiredFont + ", " + $fallbackFont};
}

@function font-weight($name) {
  @return map-get(map-get($font-families, $name), weight);
}

// -------------------------------
// How to use this:
//
// h1 { @extend .title;   }
// h2 { @extend .heading; }
// p  { @extend .base; }
// ---------------------------------

// -------------------------------
// Define site settings here: 
//    base
//    font-families
//    font specs
//---------------------------------

$base: (
  font-size: 1rem,
  base-multiplier: 1.5,
  unit: 1rem * 1.5, // font * base-multiplier
  font-family: "Avenir Roman"
);

$font-families: (
  avenir-roman: (
    name:     "Avenir Roman",
    weight:   300,
    filename: "yeahhh",
    fallback: unquote("Arial, serif")
  ),
  avenir-heavy: (
    name: "Avenir Heavy",
    weight: 700,
    filename: "foooo",
    fallback: unquote("Arial, serif")
  )
);

$fonts: (
  base: (
    size:   size(1),
    family: avenir-roman
  ),
  title: (
    size:   size(4),
    family: avenir-heavy
  ),
  heading: (
    size:   size(3),
    family: avenir-heavy
  )
);

// -----------------------------------
// This generate classes for each for spec
// -----------------------------------
@each $font-name, $font-spec in $fonts {
  $size: map-get($font-spec, size);
  $family: map-get($font-spec, family);
  .#{$font-name} {
    font-size:   $size;
    line-height: line-height($size);
    font-family: font-family($family);
    font-weight: font-weight($family);
  }
}

output.css

.base {
  font-size: 1rem;
  line-height: 1.5rem;
  font-family: Avenir Roman, Arial, serif;
  font-weight: 300;
}

.title {
  font-size: 4rem;
  line-height: 6rem;
  font-family: Avenir Heavy, Arial, serif;
  font-weight: 700;
}

.heading {
  font-size: 3rem;
  line-height: 4.5rem;
  font-family: Avenir Heavy, Arial, serif;
  font-weight: 700;
}