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Or compile to JavaScript for the web Optimized for UI Mature and complete async-await for user interfaces containing event-driven code, paired with isolate-based concurrency A programming language optimized for building user interfaces with features such as the spread operator for expanding collections, and collection if for customizing UI for each platform A programming language that is easy to learn, with a familiar syntax Productive Development Make changes to your source code iteratively, using hot reload to instantly see the effect in the running app Write code using a flexible type system with rich static analysis and powerful, configurable tooling Do profiling , logging , and debugging with your code editor of choice Fast on all platforms AOT-compile apps to native machine code for instant startup Target the web with complete, mature, fast compilers for JavaScript Run backend code supporting your app, written using a single programming language Optimized for UI Mature and complete async-await for user interfaces containing event-driven code, paired with isolate-based concurrency A programming language optimized for building user interfaces with features such as the spread operator for expanding collections, and collection if for customizing UI for each platform A programming language that is easy to learn, with a familiar syntax Productive development Make changes to your source code iteratively, using hot reload to instantly see the effect in the running app Write code using a flexible type system with rich static analysis and powerful, configurable tooling Do profiling , logging , and debugging with your code editor of choice Fast on all platforms AOT-compile apps to native machine code for instant startup Target the web with complete, mature, fast compilers for JavaScript Run backend code supporting your app, written using a single programming language Try Dart in your browser Want more practice? Try a codelab . Or download Dart . Hello, World! main () { print ( 'Hello, World!' ); } Functions // A function declaration. int timesTwo ( int x ) { return x * 2 ; } // Arrow syntax is shorthand for `{ return expr; }`. int timesFour ( int x ) => timesTwo ( timesTwo ( x )); // Functions are objects. int runTwice ( int x , Function f ) { for ( var i = 0 ; i < 2 ; i ++) { x = f ( x ); } return x ; } main () { print ( "4 times two is ${timesTwo(4)} " ); print ( "4 times four is ${timesFour(4)} " ); print ( "2 x 2 x 2 is ${runTwice(2, timesTwo)} " ); } Control flow bool isEven ( int x ) { // An if-else statement. if ( x % 2 == 0 ) { return true ; } else { return false ; } } List < int > getEvenNumbers ( Iterable < int > numbers ) { var evenNumbers = < int >[]; // A for-in loop. for ( var i in numbers ) { // A single-line if statement. if ( isEven ( i )) evenNumbers . add ( i ); } return evenNumbers ; } main () { var numbers = List . generate ( 10 , ( i ) => i ); print ( getEvenNumbers ( numbers )); } Strings main () { print ( 'a single quoted string' ); print ( "a double quoted string" ); // Strings can be combined with the + operator. print ( 'cat' + 'dog' ); // Triple quotes define a multi-line string. print ( '''triple quoted strings are for multiple lines''' ); // Dart supports string interpolation. const pi = 3.14 ; print ( 'pi is $pi ' ); print ( 'tau is ${2 * pi} ' ); } Collection literals // A list literal. var lostNumbers = [ 4 , 8 , 15 , 16 , 23 , 42 ]; // A map literal. var nobleGases = { 'He' : 'Helium' , 'Ne' : 'Neon' , 'Ar' : 'Argon' , }; // A set literal. var frogs = { 'Tree' , 'Poison dart' , 'Glass' , }; main () { print ( lostNumbers . last ); print ( nobleGases [ 'Ne' ]); print ( frogs . difference ({ 'Poison dart' })); } Classes // Abstract classes can't be instantiated. abstract class Item { use (); } // Classes can implement other classes. class Chest < T > implements Item { List < T > contents ; // Constructors can assign arguments to instance variables using `this`. Chest ( this . contents ); use () => print ( " $this has ${contents.length} items." ); } class Sword implements Item { int damage = 5 ; use () => print ( " $this dealt $damage damage." ); } // Classes can extend other classes. class DiamondSword extends Sword { int damage = 50 ; } main () { // The 'new' keyword is optional. var chest = Chest < Item >([ DiamondSword (), Sword (), ]); chest . use (); for ( var item in chest . contents ) { item . use (); } } Compute π import 'dart:math' show Random ; main () async { print ( 'Compute π using the Monte Carlo method.' ); await for ( var estimate in computePi (). take ( 100 )) { print ( 'π ≅ $estimate ' ); } } /// Generates a stream of increasingly accurate estimates of π. Stream < double > computePi ({ int batch = 100000 }) async * { var total = 0 ; var count = 0 ; while ( true ) { var points = generateRandom (). take ( batch ); var inside = points . where (( p ) => p . isInsideUnitCircle ); total += batch ; count += inside . length ; var ratio = count / total ; // Area of a circle is A = π⋅r², therefore π = A/r². // So, when given random points with x ∈ <0,1>, // y ∈ <0,1>, the ratio of those inside a unit circle // should approach π / 4. Therefore, the value of π // should be: yield ratio * 4 ; } } Iterable < Point > generateRandom ([ int seed ]) sync * { final random = Random ( seed ); while ( true ) { yield Point ( random . nextDouble (), random . nextDouble ()); } } class Point { final double x , y ; const Point ( this . x , this . y ); bool get isInsideUnitCircle => x * x + y * y <= 1 ; } -- Terms Security Privacy Site CC BY 4.0...