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## 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?
v0.2
### How far ahead is the project?
The Java-bytecode compiler is almost complete.
A few features are missing and the compiler is not as fast as I would like.
However, programs can be written to try out Lux and get a feeling for the language.
### How can I use it?
Download the 0.2 compiler from here: https://github.com/LuxLang/lux/releases/download/0.2.0/lux-jvm-0.2.0-standalone.jar
Once you download the compiler, you'll want to create a directory named "source" in the same directory where the compiler is located.
You can run the compiler like this:
java -jar -Xss4m lux-jvm-0.2.0-standalone.jar program
The **program** module is already inside **source/** to make it easier to start.
##### Note: You can download all the files inside the source/ directory in this repo to get started.
This will generate a directory named "target" and put all the .class files there.
Then, you can run the program like this:
cd target/jvm/ && java -jar program.jar
### What's the license?
Eclipse Public License v1.0
## What's interesting about the language?
### Inspirations
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.
### Types
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.
However, most of the types in the prelude are generated via several macros that provide a more pleasant syntax to types.
If you wonder what types look like without makeup, feel free to read the first few hundred lines of lux.lux.
### Module system
The module system is heavily inspired by ML, and both signatures & structures are supported.
The main difference between Lux and ML is that ML separates signatures & structures from the rest of the language, whereas Lux implements them on-top of the base language.
How?
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 it's argument.
This means that 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.
Also, by hosting the module system on top of records, which are regular values, you get the further benefit that structures can be parameterized at runtime just like any other data-structures.
You can also write functions that take and return structures (as Functors do in ML) and you can generate structures on the fly.
### Functional programming
While the means to do Java-interop will be provided (and there are already a few ways to do it that you can look-up inside lux.lux), 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).
e.g.
(let [inc (i+ 1)]
(map inc (list 1 2 3 4 5)))
### Code portability
Many languages nowadays support compilation to multiple platforms (e.g. Haskell, Scala, Clojure).
However, sharing code between platforms can be a pain in the neck due to the following reasons:
* differences in features between platforms
* the languages weren't originally designed with the goal of running both native/JVM and in JavaScript
Lux is being designed from the ground-up to target multiple platforms and achieve maximum reusability of code with minimum hassle.
The mechanism hasn't been added yet to the language (mainly because there's only 1 compiler at the moment), but it will come pretty soon in one of the upcoming releases.
### Macros
Unlike in most other lisps, Lux macros are monadic.
The **(Lux a)** type is the one responsible for the magic by treading **Compiler** instances through macros.
Macros must have the **Macro** type and then be declared as macros.
However, just using the **defmacro** macro will take care of it for you.
Alternatively, you can use the **defsyntax** 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 & 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 them inside pattern-matching:
(case (: (List Int) (list 1 2 3))
(#Cons [x (#Cons [y (#Cons [z #Nil])])])
(#Some ($ int:* x y z))
_
#None)
(case (: (List Int) (list 1 2 3))
(\ (list x y z))
(#Some ($ int:* x y z))
_
#None)
There is also the special **\or** macro, which introduces *or patterns*:
(deftype Weekday
(| #Monday
#Tuesday
#Wednesday
#Thursday
#Friday
#Saturday
#Sunday))
(def (weekend? day)
(-> Weekday Bool)
(case day
(\or #Saturday #Sunday)
true
_
false))
##### Please note: \ and \or are just macros like any other and anyone can implement them.
I'll be adding more useful pattern-matching macros in upcoming releases of the language.
If you want to see how they work, just check out their implementation inside lux.lux
### Is there a community for this?
Lux was born recently.
Come join the budding community by joining the discussion group at: https://groups.google.com/forum/#!forum/lux-programming-language
If you want to communicate with me directly, just email me at luxlisp@gmail.com
### How can I edit Lux code?
Check out the Emacs plugin for it: https://github.com/LuxLang/lux-mode
## Where do I learn Lux?
Just head to the wiki and check out the documentation for the currently available modules, and the tutorials.
## Caveats
### Errors
The compiler is not fully stable so you might get an error if you do anything funny.
Also, the error messages could really use an overhaul, so any error message you get will probably startle you.
Don't worry about it, version 0.3 will improve error reporting a lot.
If you have any doubts, feel free to ask/complain in the Google Group.
### Tags
Tags that are unprefixed will just assume the prefix of the current module you're in.
If you want to write variants/records with tags from lux.lux, you must do 1 of the following 2 alternatives:
* Fully prefix them: #lux;Cons
* Use the ; short-cut: #;Cons
##### Copyright (c) 2015 Eduardo Julian. All rights reserved.
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