Introduction to Dart

"Dart is a client-optimized language for fast apps on any platform." — dart.dev

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What Is Dart?

Dart is a statically typed, object-oriented programming language created by Google in 2011. It compiles to native machine code (for mobile/desktop), JavaScript (for web), and runs on the Dart VM (for servers/CLIs).

Why Dart?

Feature	Benefit
Sound null safety	Eliminates entire classes of null-pointer bugs
AOT + JIT compilation	Fast startup (AOT) + hot reload during development (JIT)
Strong typing + inference	Safety without verbosity
Async-first design	async/await built into the language
Flutter's language	Required for Flutter — the most popular cross-platform UI framework
Familiar syntax	Feels like Java/Kotlin/Swift — easy to pick up

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Dart vs Other Languages

If you know...     Dart will feel like...
──────────────────────────────────────────
Java               Cleaner Java with modern features
Kotlin             Very similar — Dart is simpler in some ways
Swift              Close cousin — similar null safety model
JavaScript         Structured JS with types (and much safer)
Python             More verbose but catches errors at compile time

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Setting Up

Option 1 — Install Dart SDK (standalone)

# macOS (Homebrew)
brew tap dart-lang/dart
brew install dart

# Windows (Chocolatey)
choco install dart-sdk

# Linux (apt)
sudo apt-get update
sudo apt-get install dart

# Verify
dart --version
# Dart SDK version: 3.x.x

Option 2 — Install Flutter (includes Dart)

# Flutter includes the Dart SDK
# https://flutter.dev/docs/get-started/install
flutter --version
dart --version  # works after installing Flutter

Editor Setup

• VS Code: Install the Dart extension
• IntelliJ / Android Studio: Dart plugin built-in with Flutter plugin
• Online: dartpad.dev — no install needed!

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Your First Dart Program

// hello.dart

void main() {
  print('Hello, Dart! 🎯');
}

dart run hello.dart
# Hello, Dart! 🎯

A More Interesting Example

// greet.dart

void main() {
  var name = 'Flutter Developer';
  var year = DateTime.now().year;

  print('Hello, $name!');
  print('Welcome to Dart in $year.');
  print('2 + 2 = ${2 + 2}');

  // Call a function
  greet(name: 'World', loud: true);
}

void greet({required String name, bool loud = false}) {
  var message = 'Hello, $name!';
  print(loud ? message.toUpperCase() : message);
}

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Creating a Dart Project

# Create a new CLI app
dart create my_app
cd my_app

# Project structure:
# my_app/
# ├── bin/
# │   └── my_app.dart    ← entry point
# ├── lib/
# │   └── my_app.dart    ← library code
# ├── test/
# │   └── my_app_test.dart
# └── pubspec.yaml        ← project config & dependencies

pubspec.yaml

name: my_app
description: My first Dart app
version: 1.0.0

environment:
  sdk: '>=3.0.0 <4.0.0'

dependencies:
  http: ^1.1.0        # add packages here

dev_dependencies:
  lints: ^3.0.0
  test: ^1.24.0

# Install dependencies
dart pub get

# Run the app
dart run

# Run tests
dart test

# Format code
dart format .

# Analyze for issues
dart analyze

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How Dart Compiles

Source (.dart)
     │
     ├──► JIT (Dart VM)         ← Development: fast hot reload
     │
     ├──► AOT (native binary)   ← Production: fast startup, small size
     │         dart compile exe app.dart
     │
     └──► JavaScript             ← Web: runs in browsers
               dart compile js app.dart

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Key Language Concepts at a Glance

// Everything is an object (even int, bool, null)
int x = 42;
x.toString();   // '42'
x.runtimeType;  // int

// Strong type inference
var name = 'Dart';        // inferred as String
var count = 0;            // inferred as int
var ratio = 3.14;         // inferred as double
var active = true;        // inferred as bool

// Sound null safety — nulls must be explicit
String nonNullable = 'hello';   // can NEVER be null
String? nullable = null;        // explicitly nullable

// Functions are first-class objects
var double = (int x) => x * 2;
print(double(5));  // 10

// Async built-in
Future<String> fetchData() async {
  await Future.delayed(Duration(seconds: 1));
  return 'Data loaded!';
}

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Dart's Type Hierarchy

Object
├── num
│   ├── int
│   └── double
├── String
├── bool
├── List<E>
├── Set<E>
├── Map<K, V>
├── Function
├── Symbol
├── Record
└── Null      (only null has type Null)

In Dart, everything is an object — even null, 42, and true.

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Comments

// Single-line comment

/*
  Multi-line comment
  spans multiple lines
*/

/// Documentation comment (shown in IDE tooltips)
/// Supports [markdown] and references to [ClassName.method].
///
/// Example:
/// ```dart
/// var result = add(1, 2); // 3
/// ```
int add(int a, int b) => a + b;

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Summary

• Dart is statically typed, null-safe, and object-oriented
• It compiles to native code, JS, or runs on the VM
• It's the language of Flutter — learning Dart = learning Flutter
• The main() function is the entry point of every program
• Use dartpad.dev to experiment without installing anything