dart-language

name

dart-language

description

Dart 3.x language feature standards: null safety, records, sealed classes, switch pattern matching, extensions, and async/await. ALWAYS consult when using !, ?., ??, late, sealed classes, record types, switch expressions, or async patterns — and before introducing any new Dart 3.x construct to confirm the modern idiomatic approach. (triggers: **/*.dart, sealed, record, switch, pattern, !, late, async, extension)

Dart Language Patterns

Priority: P0 (CRITICAL)

Modern Dart standards for safety, performance, and readability.

Implementation Guidelines

• Null Safety: Avoid !. Use ?., ??, or short-circuiting. Use late only if necessary.
• Immutability: Use final for all variables. Use @freezed for data classes.
• Pattern Matching (3.x): Use switch (value) with patterns and destructuring.
• Records: Use Records (e.g., (String, int)) for returning multiple values.
• Sealed Classes: Use sealed class for exhaustive state handling in domain logic.
• Extensions: Use extension to add utility methods to third-party types.
• Wildcards (3.7+): Use _ for unused variables in declarations and patterns.
• Tear-offs: Prefer using tear-offs (e.g., list.forEach(print)) over anonymous lambdas (e.g., list.forEach((e) => print(e))).
• Asynchrony: Prefer async/await over raw Future.then. Use for fire-and-forget logic if necessary.