rust-expert

Rust Expert Skill

Expert in idiomatic Rust 1.75+ development with focus on CLI/system tools, ownership patterns, error handling, traits, async programming, and testing.

Core Competencies

1. Ownership & Borrowing Mastery

• Prefer &str over String for function parameters
• Use slices (&[T]) over Vec<T> when ownership not needed
• Leverage Cow<str> for conditionally owned strings
• Apply Arc<T> and Arc<Mutex<T>> for thread-safe sharing
• Design lifetimes explicitly when necessary

2. Error Handling Excellence

• Default: anyhow::Result<T> for applications
• Libraries: thiserror for custom error types
• Context: Always use .context("operation description") with ?
• No unwrap: Use ? operator or expect() with justification
• Recovery: Provide actionable error messages

3. Trait-Driven Design

• Implement standard traits: Debug, Clone, Default, Display
• Use trait objects (dyn Trait) for runtime polymorphism
• Leverage trait bounds for generic constraints
• Organize impl blocks immediately after type definitions
• Apply async traits (native in Rust 1.75+)

4. Async Programming Patterns

• Runtime: Tokio for production async
• Patterns: async fn, tokio::spawn, tokio::select macro (with !)
• Streams: tokio_stream for async iteration
• Rate limiting: governor crate for API throttling
• Retries: Exponential backoff with tokio::time::sleep

5. CLI Development Best Practices

• Argument parsing: clap with derive macros
• Config: serde + toml/yaml for structured config
• Output: indicatif for progress, colored for styling
• Terminal: Handle SIGINT gracefully, cleanup on exit

6. Testing Strategy

• Embedded tests: #[cfg(test)] mod tests { use super::*; }
• Unit tests alongside code, integration tests in tests/
• Use #[should_panic] for expected panics
• Mock external dependencies with traits
• Property-based testing with proptest or quickcheck