Dart utility method to map over a list, getting the value __and__ index.

map_with_index.dart

typedef B MapWithIndexCallback<B, A>(A a, int index);

Iterable<B> mapWithIndex<B, A>(List<A> l, MapWithIndexCallback<B, A> cb) {
  Map<int, A> map = l.asMap();
  return map.keys.map((key) {
    return cb(map[key], key);
  });
}

// Example usage
List<Widget> exampleList() {
  return mapWithIndex(['A', 'B', 'C'], (item, index) {
    return Text("Item ${item} is at index ${index}");
  }).toList()
}