lux

lux is a small language built to be a great first language and then to be outgrown. Every feature is the simplest version of something shared by Rust, Swift, and Go, so what you learn here carries straight over when you move on to one of those. The few hard ideas lux leaves out — ownership, classes, goroutines — are the lessons those bigger languages exist to teach.

The full language fits on one page. Read learn-lux.md: it is the reference, the tutorial, and the test corpus all at once — the suite runs every example in it. The same material is built into the binary, so once lux is installed you can read it in your terminal with lux learn.

Installing

On macOS or Linux, install a prebuilt lux with one command — no Rust toolchain needed:

curl -LsSf https://anderix.com/lux/install | sh

That URL is a stable front door to the latest release: running it again updates in place, and once lux is installed lux update does the same from the binary itself. To remove it again:

curl -LsSf https://anderix.com/lux/uninstall | sh

If you already have Rust, you can install from crates.io instead. The crate is named luxc; the command it installs is lux:

cargo install luxc

Remove that build with cargo uninstall luxc.

Running a program

lux run examples/tour.lux

lux run interprets a program directly. lux convert <rust|swift|go> <file.lux> prints your program as real source in that language, and lux build <file.lux> runs the Rust translation through rustc to a native binary.

Playing a crawl

lux crawl

lux crawl writes a small, playable text adventure into a crawl/ folder and tells you how to play it. The whole world is the world.lux it leaves you — open it, and the rooms, doors, and the torch in the cellar are all there in plain lux, yours to change. lux learn crawl walks through how one is built.

Learning the language

The reference travels inside the binary. lux learn opens a menu of short topics and guided lessons. Each topic is a one-screen card — lux learn match prints the idea, a runnable example, and an experiment to try; add more for the deeper why, the universal name for the concept, and where it goes in Rust, Swift, and Go. lux learn basics lays out the handful of shapes every procedural language shares, so the next language is mostly new spelling, and lux learn tour reads the whole thing top to bottom. Every example is real lux you can paste into a file and run. And when a program hits an error, the diagnostic points you at the topic that explains it — a non-exhaustive match ends with help: run lux learn match — so you learn the idea at the moment you need it.

lux learn               # the menu
lux learn enums         # one topic, as a card
lux learn enums more    # the deeper level
lux learn basics        # the shapes every language shares
lux learn tour          # the whole language

Building from source

lux is written in Rust with no dependencies.

cargo build --release
./target/release/lux run examples/hello.lux

Status

Early, but the teaching surface is complete. lux run covers the core — print, let/var, the four basic types with honest conversions, arithmetic, strings, if/else, while, for ... in, ranges, arrays, functions with recursion, and scope — then your own types (structs, enums with associated values, and exhaustive match), and no null: Option<T> and Result<T, E> instead. The outside world is modeled as those same two shapes — readFile, writeFile, args, readLine, input, print/eprint, and run(program, [args]) returning Result<Output, string> — so fallible I/O is something you handle rather than a crash. All three transpiler backends are live: lux convert turns any of this into idiomatic Rust, Swift, or Go, each leaning on what that language already has, and lux build compiles the Rust to a native binary. Every feature is runnable and translatable to all three.

Around that core sits how you learn it. lux learn is the built-in reference — a two-level card-and-more system, cross-referenced from error messages, that also reads as guided lessons and a full tour. lux magic answers "how do I…?" with small working spells, each carrying a trail back to the topic that explains it. lux crawl drops a small text adventure whose whole world is one lux file you play by running and change by editing — with a tutorial-free fast track (lux magic room, exit, thing, command) for the tinkerer who would rather skip straight to changing it. And lux update fetches the latest release in place.

For the fuller history, see CHANGELOG.md and the scope notes at the bottom of learn-lux.md.

License

MIT. Written by David M. Anderson with AI assistance.