The Lux Programming Language
Clojure Emacs Lisp

What is Lux?

Lux is a new programming language in the making.

It's meant to be a functional, statically-typed Lisp that will run on several platforms, such as the Java Virtual Machine and JavaScript interpreters.

What's the current version?


How far ahead is the project?

Lux is in the beta stage.

The JVM compiler is pretty stable and the standard library has grown to a respectable size.

Also, new experimental support for Android has been added.

How can I use it?

You should use the Leiningen plugin for Lux to compile your programs and manage your dependencies.

You can find it here:

After compiling your program, this will generate a directory named "target" and put all the .class files there.

Then, you can run the program like this:

java -jar target/jvm/program.jar


To take a look at sample Lux projects, check these repositories:

The luxdoc program was actually used to generate the documentation for the standard library in the wiki (located here:

What's the license?

Mozilla Public License v2.0

What's interesting about the language?


The language is mostly inspired by the following 3 languages:

  • Haskell (functional programming)
  • Clojure (syntax, overall look & feel)
  • ML (module system)

The compiler is even implemented in Clojure.


They are implemented as plain-old data-structures whose expressions get eval'ed by the compiler and integrated into the type-checker.

That means it's actually possible to generate types via functions and macros.

Module system

The module system is heavily inspired by ML, and both signatures and structures are supported.

The main difference between Lux and ML is that ML separates signatures and structures from the rest of the language, whereas Lux implements them on top of the base language.


By implementing signatures as record-types and structures as actual records.

But, why not just use type-classes?

Haskell's type-class system forces the user to only specify 1 instance for any given type-class and its argument.

If there are more than 1 possible valid instances (as is the case for Monoid of Int), you have to resort to newtype hacks to be able to provide alternative implementations.

By using a system like ML's, that problem is averted.

Additionally, by hosting the module system on top of records, which are regular values, you get the further benefit that structures can be parameterized at run-time just like any other value.

You can also write functions that take and return structures (as functors do in ML), and you can generate structures on the fly.

Also, Lux now offers a mechanism for easy polymorphism, just like Haskell's type-classes, but built upon it's module system, thanks to the lux/type/auto module and its ::: macro.

You can learn more about that by reading the book and the documentation.

Functional programming

While the means to do Java-interop are provided, Lux is commited to functional programming.

Functions are curried and partial application is as simple as just applying a function to less arguments than it needs (as in Haskell).


(map (i.+ 1) (list 1 2 3 4 5))


Unlike in most other lisps, Lux macros are monadic.

The (Lux a) type is the one responsible for the magic by threading Compiler instances through macros.

You can use macro: to define these monadic macros.

Alternatively, you can use the syntax: macro, which also offers monadic parsing of AST tokens for convenience.

Custom pattern-matching

Wait... wut?

Custom pattern-matching basically means that you can use macros to provide custom syntax and features on top of the pattern-matching macro case.

For instance, the list and list& macros are used to build lists. But you can also use them to destructure lists inside pattern-matching:

(case (: (List Int) (list 1 2 3))
  (#Cons x (#Cons y (#Cons z #Nil)))
  (#Some ($_ i.* x y z))


(case (: (List Int) (list 1 2 3))
  (^ (list x y z))
  (#Some ($_ i.* x y z))


There is also the special ^or macro, which introduces or patterns:

(type: Weekday

(def: (weekend? day)
  (-> Weekday Bool)
  (case day
    (^or #Saturday #Sunday)


Please note: ^ and ^or are just macros like any other and anyone can implement them.

Is there a community for this?

Come join the discussion group at:!forum/lux-programming-language

If you want to communicate with me directly, just email me at

Also, you can chat with us on Gitter: Join the chat at

How can I edit Lux code?

Check out the Emacs plugin for it:

Where do I learn Lux?

The main resource is the book:

It will always be up-to-date with the latest stable version of the language.

Also, you can head to the wiki and check out the documentation for the currently available modules:

Finally, you can check out the Lux DevLog, where I talk about different topics related to Lux and post tutorials:

How can I contribute?

For starters, you can check out the Trello board for Lux development:

I'll be putting there tasks that people can contribute to; both in the compiler and outside (like plugins for editors).

Writing libraries in Lux will also help a lot in making this a more practical language for day to day use.

Communication is done over Gitter and the Google group.

Copyright (c) 2014-2017 Eduardo Julian. All rights reserved.