Rust Generics Best Practices
Practical generics guide for type parameters and constraints with runnable examples and review-ready checklists.
Topic: Generics
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Rust Generics Best Practices
Problem
Teams often struggle with type parameters and constraints when code grows quickly and review cycles shorten. This guide turns that into a repeatable process.
Diagnostic checklist
- Define one concrete failure mode before changing code.
- Reduce to a minimal example first.
- Validate assumptions around ownership, mutability, and API boundaries.
- Keep fix scope small and testable.
Runnable example
fn main() {
let data = vec![1, 2, 3, 4];
let sum: i32 = data.iter().sum();
println!("sum={}", sum);
}Counterexample
fn main() {
let s = String::from("hello");
let moved = s;
println!("{}", s); // moved value
}How to decide in production
1. Start with correctness and explicit ownership.
2. Add instrumentation before optimizing.
3. Keep interfaces small and typed.
4. Record tradeoffs directly in code and PR description.