How to Code in Rust Using AI

In short: say the Rust edition and “no extra crates”, give examples, ask for #[test] functions, run cargo test and cargo clippy.

Why Rust with AI

Rust is used where speed and safety matter: browsers, cloud infrastructure, command-line tools. Companies like Microsoft, Amazon and Cloudflare use it. The compiler rejects many mistakes before the code runs, so AI errors show up early.

What you need

• rustup: the official installer; it gives you rustc and cargo.
• cargo: builds, tests and runs Rust projects. Tests are built in.
• clippy: Rust's linter: rustup component add clippy.
• IDE + assistant: VS Code with rust-analyzer + Copilot or Claude Code, or RustRover with Copilot.

How it flows

Install and set up

1. Install Rust from rustup.rs. (Linux/Mac: curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh; Windows: run rustup-init.exe.)
2. Check: cargo --version.
3. Add clippy: rustup component add clippy.
4. Create a library: cargo new upi --lib.

Step 1 — the prompt

Step 2 — the code with tests (tested here)

//! Check the shape of a UPI ID like "ravi.b@okhdfc". Built with an AI assistant, then tested.

/// Returns true if `id` looks like a valid UPI ID:
/// name (2-256 chars: letters, digits, '.', '-', '_') + '@' + handle (2-64 letters).
pub fn is_valid_upi(id: &str) -> bool {
    let id = id.trim();
    let Some((name, handle)) = id.split_once('@') else {
        return false;
    };
    let name_ok = (2..=256).contains(&name.len())
        && name
            .chars()
            .all(|c| c.is_ascii_alphanumeric() || matches!(c, '.' | '-' | '_'));
    let handle_ok = (2..=64).contains(&handle.len()) && handle.chars().all(|c| c.is_ascii_alphabetic());
    name_ok && handle_ok
}

#[cfg(test)]
mod tests {
    use super::is_valid_upi;

    #[test]
    fn valid_ids() {
        assert!(is_valid_upi("ravi.b@okhdfc"));
        assert!(is_valid_upi(" 9876543210@ybl "));
    }

    #[test]
    fn invalid_ids() {
        assert!(!is_valid_upi("ravi"));             // no @
        assert!(!is_valid_upi("ravi@ok@hdfc"));     // two @
        assert!(!is_valid_upi("r@okhdfc"));         // name too short
        assert!(!is_valid_upi("ravi b@okhdfc"));    // space in name
        assert!(!is_valid_upi("ravi@ok1"));         // digit in handle
    }
}

cargo test
# -> test tests::valid_ids ... ok
# -> test tests::invalid_ids ... ok
# -> test result: ok. 2 passed
cargo clippy
# -> no warnings

Settings and config

1. VS Code: install rust-analyzer; it shows compiler errors as you type.
2. Rules file: “Rust 2021, std only unless asked, no unwrap() in library code, add #[test]s”.
3. CI: cargo fmt --check, cargo clippy -- -D warnings, cargo test.

Watch out (common AI mistakes in Rust)

Quick quiz

Save tokens and money

Let the compiler do the first review for free. Paste only the first compiler error, not all of them; fixing one often fixes the rest.

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