Standards & Conventions 📏

Why conventions matter

Imagine a library where every shelf used a different sorting system. That is a codebase without conventions. Conventions are not bureaucracy; they are kindness to the next reader, and the next reader is usually you, three months from now, at midnight, hunting a bug.

Naming things 🏷️

Different languages chose different casing styles, and each community treats its choice as law. Rust's rules:

Beyond casing: names should say what a thing is or does. days_until_launch beats d. The compiler does not care. Humans care enormously.

Formatting: let the robot do it 🤖

Where do braces go? Tabs or spaces? Programmers wasted decades arguing. The modern answer: an auto-formatter rewrites your code into the community's one agreed style, and everyone moves on with their lives. In Rust:

cargo fmt      # reformat the whole project, perfectly, in a second
cargo clippy   # the linter: flags working-but-unidiomatic code and explains better ways

A linter like clippy goes beyond layout: it spots patterns that work but smell ("you wrote a loop where .sum() would do"). Treat clippy as a free senior colleague. Run both before every commit and your code reviews will be about ideas, never about commas.

Semantic versioning: what 1.4.2 means 🔢

Software versions look like MAJOR.MINOR.PATCH, and the numbers are a promise called semver:

• PATCH (1.4.2 → 1.4.3): bug fixes only. Safe to update, always.
• MINOR (1.4.2 → 1.5.0): new features, nothing existing breaks.
• MAJOR (1.4.2 → 2.0.0): breaking changes. Read the notes before updating.

A 0.x version means "still finding its shape, anything may change." When Cargo lists rand = "0.9" in Cargo.toml, this grammar is what the numbers speak. Rust itself takes the promise unusually seriously: code that compiled on Rust 1.0 in 2015 still compiles today.

Documentation: the README and friends 📖

Every project's front door is a README file: what this is, how to run it, how to help. Beyond that, Rust has documentation comments: write /// above a function and cargo doc builds a documentation website from your comments automatically. The beautiful std library docs you will use daily are generated exactly this way. Rule of thumb: document why, let the code say what.

Licenses: the legal layer of open source ⚖️

Public code is not automatically free to use; the license file grants permission. You mostly need to recognize three families:

• MIT / Apache-2.0: "use this for almost anything, keep the credit notice." Business-friendly. The Rust ecosystem's default is dual-licensing under both.
• GPL: "use freely, but derivative software must also share its source." Powers Linux.
• No license file: legally means all rights reserved. Look but do not touch.

The three-letter philosophies 🧭

You will hear these acronyms in every code review of your life:

• DRY (Don't Repeat Yourself): if you paste the same code a third time, extract a function. One place to fix, not five.
• KISS (Keep It Simple): the clever one-liner loses to the boring five-liner everyone understands. Simple survives.
• YAGNI (You Aren't Gonna Need It): build what today needs, not what tomorrow might. Speculative features are where projects go to die.