Dart

Appeared in:
2011
Influenced by:
Paradigm:
Typing discipline:
File extensions:
.dart
Versions and implementations (Collapse all | Expand all):
Programming language

Dart is an open-source Web-oriented programming language developed by Google. The ultimate goal of the language is to replace JavaScript as the universal language for web development.

For now, there are three ways to run Dart programs:

  • compile to JavaScript using dart2js and run in any browser.
  • run Dart code directly using Dartium — a version of Chromium with built-in Dart VM.
  • use standalone Dart VM (shipped with Dart SDK) to run Dart code in command-line environment.

Elements of syntax:

Inline comments //
Non-nestable comments /* */
Case-sensitivity yes
Variable identifier regexp [_a-zA-Z][_a-zA-Z0-9]*
Variable assignment varname = value
Variable declaration type variable
Variable declaration with assignment type variable = value
Block { ... }
Physical (shallow) equality ==
Physical (shallow) inequality !=
Comparison < > <= >=
Function definition returntype f(type1 p1, type2 p2, ...)
Function call f(a, b, ...)
Function call with no parameters f()
Sequence ,
If - then if (condition) ...
If - then - else if (condition) ... else ...
Loop forever while (true) ...
While condition do while (condition) ...
Do until condition do ...while (!condition)
For each value in a numeric range, 1 increment for (int i = 1; i <= 10; i++) ...
For each value in a numeric range, 1 decrement for (int i = 10; i >= 1; i--) ...

Dart logo
Dart logo

Links:

Examples:

Hello, World!:

Example for versions Dart 1.1.1

The “fat arrow” ( => expr; ) syntax is a shorthand for { return expr; }. 

main() => print("Hello, World!");

Factorial:

Example for versions Dart 1.1.1

This example uses recursive factorial definition. int datatype is an integer of arbitrary size. 

int factorial(int n) => n == 0 ? 1 : n * factorial(n - 1);

main() {
  for (int i = 0; i <= 16; ++i) {
    print('$i! = ${factorial(i)}');
  }
}

Factorial:

Example for versions Dart 1.1.1

This example uses iterative factorial definition. 

main() {
  int fact = 1;
  for (int i = 0; i <= 16; ++i, fact *= i) {
    print('$i! = $fact');
  }
}

Fibonacci numbers:

Example for versions Dart 1.1.1

This example uses recursive definition of Fibonacci numbers. Note that the language requires explicit conversion from int to String. 

int fibonacci(int n) => n <= 2 ? 1 : fibonacci(n - 2) + fibonacci (n - 1);

main() {
  String output = "";
  for (int i = 1; i <= 16; ++i) {
    output += fibonacci(i).toString() + ", ";
  }
  print(output + "...");
}

Quadratic equation:

Example for versions Dart 1.1.1 
import 'dart:io';
import 'dart:math' show sqrt;

int readInt() {
  String input = stdin.readLineSync();
  return int.parse(input);
}

main() {
  int A, B, C;
  try {
    A = readInt();
    B = readInt();
    C = readInt();
  }
  on FormatException {
    print("Coefficient is not a number.");
    return;
  }
  if (A == 0) {
    print("Not a quadratic equation.");
    return;
  }
  int D = B * B - 4 * A * C;
  double p1 = - B / 2.0 / A;
  double p2 = sqrt(D.abs()) / 2.0 / A;
  if (D == 0) {
    print("x = $p1");
  } else {
    if (D > 0) {
      print("x1 = ${p1 + p2}");
      print("x2 = ${p1 - p2}");
    } else {
      print("x1 = ($p1, $p2)");
      print("x2 = ($p1, ${-p2})");
    }
  }
}

CamelCase:

Example for versions Dart 1.1.1

splitMapJoin splits the string into parts that match the pattern and parts that don’t match it, converts each part using corresponding function (in this case capitalizes matches and removes non-matches), and combines the results into a new string. 

import 'dart:io';

main() {
  String text = stdin.readLineSync().toLowerCase();
  String capitalize(Match m) => m[0].substring(0, 1).toUpperCase() + m[0].substring(1);
  String skip(String s) => "";
  print(text.splitMapJoin(new RegExp(r'[a-z]+'), onMatch: capitalize, onNonMatch: skip));  
}