Switch Expression Example

main.dart

import 'package:flutter/material.dart';

void main() => runApp(
      MaterialApp(
        debugShowCheckedModeBanner: false,
        home: Scaffold(
          body: Center(
            child: FutureBuilder(
              future: Future<String>.delayed(
                  const Duration(seconds: 3), () => 'Hello World!'),
              builder: (context, snapshot) => switch (snapshot) {
                AsyncSnapshot(hasData: true, data: final d) => Text(d!),
                AsyncSnapshot(hasError: true) => const Text('Error'),
                AsyncSnapshot() => const CircularProgressIndicator.adaptive()
              },
            ),
          ),
        ),
      ),
    );