[<img src="https://github.com/justinethier/husk-scheme/raw/master/docs/husk-scheme.png" alt="husk-scheme">](http://justinethier.github.com/husk-scheme)

Husk is a dialect of Scheme written in Haskell that implements a superset of the [R<sup>5</sup>RS standard](http://www.schemers.org/Documents/Standards/R5RS/HTML/) and a large portion of the [R<sup>7</sup>RS-small](r7rs.org) language. Advanced features are provided including continuations, hygienic macros, libraries, and a full numeric tower.

Husk may be used as either a stand-alone interpreter or as an extension language within a larger Haskell application. By closely following the R<sup>5</sup>RS standard, the intent is to develop a Scheme that is as compatible as possible with other R<sup>5</sup>RS Schemes. Husk is mature enough for use in production applications, however it is not optimized for performance-critical applications. 

Scheme is one of two main dialects of Lisp. Scheme follows a minimalist design philosophy: the core language consists of a small number of fundamental forms which may be used to implement other built-in forms. Scheme is an excellent language for writing small, elegant programs, and may also be used to write scripts or embed scripting functionality within a larger application.

More information is available on the [husk website](http://justinethier.github.com/husk-scheme).

Installation
------------

1. <b>Prerequisites</b>: You will need the [Haskell Platform](http://hackage.haskell.org/platform/) if you don't already have a recent copy installed.

2. <b>Install Husk</b> using [cabal](http://www.haskell.org/cabal/):

        cabal update
        cabal install husk-scheme

3. <b>Adjust your PATH</b>: Before running Husk you may also need to add the cabal executable directory to your path. On Linux this is `~/.cabal/bin`. 

4. Now you are ready to start up the interpreter:

        justin@my-pc$ huski
          _               _        __                 _                          
         | |             | |       \\\               | |                         
         | |__  _   _ ___| | __     \\\      ___  ___| |__   ___ _ __ ___   ___  
         | '_ \| | | / __| |/ /    //\\\    / __|/ __| '_ \ / _ \ '_ ` _ \ / _ \ 
         | | | | |_| \__ \   <    /// \\\   \__ \ (__| | | |  __/ | | | | |  __/ 
         |_| |_|\__,_|___/_|\_\  ///   \\\  |___/\___|_| |_|\___|_| |_| |_|\___| 
                                                                             
         http://justinethier.github.com/husk-scheme                              
         (c) 2010-2014 Justin Ethier                                             
         Version 3.18 
                                                                             
        huski> (define (hello) 'world)
        (lambda () ...)
        huski> (hello)
        world

Husk has been tested on Windows, Linux, and FreeBSD.

Documentation
-------------
The online [user manual](http://justinethier.github.io/husk-scheme/manual/index.html) provides an overview of the Scheme language as implemented by Husk, including:

 - A [getting started](http://justinethier.github.io/husk-scheme/manual/getting-started.html) guide.
 - [Instructions](http://justinethier.github.io/husk-scheme/manual/haskell-interface.html) for using the [Haskell API](http://hackage.haskell.org/package/husk-scheme) 
 - An alphabetical listing of the [Scheme API](http://justinethier.github.io/husk-scheme/manual/node106.html).

**Directory Structure**

 - **`docs`** - Documentation has been moved from here to the [`gh-pages`](http://justinethier.github.io/husk-scheme/) branch.
 - [**`examples`**](https://github.com/justinethier/husk-scheme/tree/master/examples) - Example programs, mostly written in Scheme.
 - [**`extensions`**](https://github.com/justinethier/husk-scheme/tree/master/extensions) - Haskell-based extensions to Husk.
 - [**`hs-src`**](https://github.com/justinethier/husk-scheme/tree/master/hs-src) - Haskell source code for Husk.
 - [**`lib`**](https://github.com/justinethier/husk-scheme/tree/master/lib) - Library portions of Husk written in Scheme.
 - [**`scripts`**](https://github.com/justinethier/husk-scheme/tree/master/scripts) - Build scripts for Husk and a basic Emacs integration script.
 - [**`tests`**](https://github.com/justinethier/husk-scheme/tree/master/tests) - Functional tests for Husk. These can be run automatically by using `make test` from the main Husk directory.


License
-------
Copyright (C) 2010 [Justin Ethier](http://github.com/justinethier)

Husk scheme is available under the [MIT license](http://www.opensource.org/licenses/mit-license.php).

The interpreter is based on code from the book [Write Yourself a Scheme in 48 Hours](http://en.wikibooks.org/wiki/Write_Yourself_a_Scheme_in_48_Hours) written by Jonathan Tang and hosted / maintained by Wikibooks.