Dart language first steps

dart_first_steps.dart

var _nobleGases = [0, 1];

/* Short way for functions in a single line of code, for instance:
 * bool isNoble(int atomicNumber) { 
 *   return _nobleGases[atomicNumber] != null;
 * }
 * // Becomes:
 * bool isNoble(int atomicNumber) => _nobleGases[atomicNumber] != null;
*/
bool isNoble(int atomicNumber) => _nobleGases[atomicNumber] != null;
String getPlayerName(String playerName) => playerName ?? 'Guest';
String getMyBirthday() => '07/07/1991';
double getAnyNumber() => 9 + 5.15;
void printElement(int element) {
  print(element);
}

// This is a shorthand as well for void.
/**
 * void printSomething() {
 *   print('Printing something');
 * }
 */
printSomething() => print('Printing something');
// fyi ~/ gets integer division.
printArithmeticOperation(int a, int b) => print('${a ~/ b} integer division');

/// Returns a function that adds [addBy] to the
/// function's argument.
Function makeAdder(num addBy) {
  return (num i) => addBy + i;
}

// This means returns null.
foo() {}

// This is the main function that dart recognizes and runs.
main() {
  print(isNoble(1));
  String aName;
  print(getPlayerName(aName));
  print(getMyBirthday());
  print(getAnyNumber());
  printSomething();
  printArithmeticOperation(10, 3);
  print(foo());

  var callbacks = [];
  for (var i = 0; i < 2; i++) {
    callbacks.add((int a) => print(a + i));
  }
  print(callbacks);
  callbacks.forEach((c) => c(2));

  var list = [1, 2, 3];
  print(list[0]);
  print('ForEach');
  // Pass printElement as a parameter.
  list.forEach(printElement);
  // list ForEach as "anonymous/closure/lambda" function.
  list.forEach((int element) {
    print(element);
  });

  // Anonymous function use in variables.
  var loudify = (msg) => '!!! ${msg.toUpperCase()} !!!';
  print(loudify('Hello world'));

  List colors = new List();
  colors.add('Red');
  colors.add('Orange');
  colors.add('Purple');
  colors.forEach((String color) {
    print('[${colors.indexOf(color)}] - Color: $color');
  });
  // It is the same from above but using shorthand function sintax.
  colors.forEach(
      (String color) => print('[${colors.indexOf(color)}] - Color: $color'));
  
  // Or var adderA = makeAdder(5); 
  // Where 'var' stands for any type of variable.
  Function adderA = makeAdder(5);
  // Print 10.
  print(adderA(5));
  // Prints 19 - This is because first evaluate function, then evaluates anonymous function(the one that returns).
  print(makeAdder(10)(9));
  
}