Rust Max: The Book

Set up the mold linker

Linking is one of the most time-consuming stages of a Rust build, and it has to be redone every time you test your program.

On Linux the mold linker is faster than the the default linker. Setting it up manually is not difficult, but just hard enough that I have to look it up every time.

The Rust Max CLI tool can do it instead:

rustmax install-tool mold

Use rustfmt::skip

Sometimes exact formatting is important to make code beautiful. Don't be afraid annotate with #[rustfmt::skip].

Use Option with ?

The ? operator works with Option to early-return on None, making option-heavy code much cleaner.

#![allow(unused)]
fn main() {
fn find_user_email(id: u32) -> Option<String> {
    let user = database.find_user(id)?;  // Return None if user not found
    let profile = user.get_profile()?;   // Return None if no profile
    let email = profile.email?;          // Return None if no email
    Some(email)
}
}

An alternative to match or if let statements, ? lets you chain operations that might fail, automatically propagating None up the call stack.

Put common development commands in a justfile

Almost every project has a handful of commands the developer(s) uses frequently. Put these in a justfile so the menu of commands for this project is always obvious, which can be extra helpful after years away from a project.

just runs commands listed in a file named justfile. The justfile lives your project's root directory, and is configured with a make-like syntax:

default:
    just --list

install-tools:
    cargo install mdbook
    cargo install mdbook-yapp

clean: doc-clean
    cargo clean

doc-clean:
    rm -rf out

It's a simple idea, but suprisingly useful. And don't worry that it looks like a Makefile — it is much more fun and sensible in use than make.

When you come back to a project and see there's a justfile you know to run just --list and you'll immediately see what was on the previous maintainer's mind.

$ just --list
Available recipes:
    build
    check
    clean
    default
    doc-book
    doc-build
    doc-clean
    doc-crates
    install-tools
    lint
    maint-audit
    maint-duplicates
    maint-lock-minimum-versions # useful prior to running `cargo audit`
    maint-outdated
    maint-upgrade
    prebuild
    publish
    publish-dry
    replace-version old new
    test
    test-min-version-build