Dart Type Alias

typedef AliasName<TypeParameters> = ExistingType<TypeParameters>;

// Fully bound type alias
typedef StringMap = Map<String, String>;

// Partially bound generic type alias
typedef JsonMap<T> = Map<String, T>;

// Pass-through generic type alias
typedef Matrix<T> = List<List<T>>;

// Modern function type alias
typedef StringTransformer = String Function(String input);

// Legacy function type alias (supported but discouraged)
typedef String LegacyTransformer(String input);

typedef Identifier = int;

typedef Score = double;

void main() {
  Score myScore = 95.5;
  double standardDouble = 95.5;

  // Evaluates to true. The runtime type is 'double', not 'Score'.
  print(myScore.runtimeType == double); 
  
  // Evaluates to true. They are structurally identical.
  print(myScore.runtimeType == standardDouble.runtimeType); 
  
  // Valid assignment: The compiler sees 'Score' as 'double'.
  standardDouble = myScore; 
}