lib/compass/sass_extensions/functions/sprites.rb

sprites.rb

  # Returns the names of all sprites in a sprite map.
  def sprite_names(map)
    verify_map(map, "sprite-names")
    Sass::Script::List.new(map.sprite_names.map { |sprite_name| Sass::Script::String.new(sprite_name) }, :comma)
  end
  Sass::Script::Functions.declare :sprite_names, [:map]

usage.scss

$icons: sprite-map('icons/*.png', $spacing: $default-icon-size * 8);

@each $sprite-name in sprite-names($icons) {
  .my-icon-#{$sprite-name} {
    ...
  }
}

// No need to declare a list of the icons,
// the list is instead generated dynamically.
// Add a file, re-compile and voila!