Step 1 - Typed collections

void main() {
  List<int> numbers = [1, 2, 3];
  Map<String, int> scores = {'Asha': 90, 'Rafi': 82};
  print(numbers);
  print(scores);
}

• List<int> accepts only int.
• Map<String, int> means key is String, value is int.

Step 2 - Type inference

void main() {
  var names = <String>['A', 'B'];
  var prices = <double>[9.99, 14.5];
  print(names);
  print(prices);
}

• Dart can infer types from values and generic hints.

Step 3 - Simple generic function

T identity<T>(T value) {
  return value;
}

void main() {
  print(identity<int>(5));
  print(identity<String>('hello'));
}

• Same function works for many types.

dynamic vs Object (basic)

• dynamic: no type checks at compile time, risky.
• Object: any object, but you must check/cast before specific use.
• Prefer concrete types first. Use Object if needed. Avoid dynamic unless required.

Practice tasks

• Write List<T> makePair<T>(T a, T b) and return [a, b].
• Create a typed map: Map<String, double>.
• Rewrite one dynamic variable into a safer specific type.