The husk-scheme package

[Tags: library, mit, program]

A dialect of R5RS Scheme written in Haskell. Provides advanced features including continuations, hygienic macros, a Haskell FFI, and the full numeric tower.

[Skip to ReadMe]


Versions1.0, 1.1, 1.2, 1.3, 2.0, 2.1, 2.2, 2.3, 2.4, 3.0, 3.1, 3.2, 3.2.1, 3.3, 3.4, 3.4.1, 3.4.2, 3.4.3, 3.4.4, 3.5.1, 3.5.2,,,, 3.5.3,,, 3.5.4, 3.5.5, 3.5.6, 3.5.7, 3.6, 3.6.1, 3.6.2, 3.6.3, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13, 3.14, 3.15, 3.15.1, 3.15.2, 3.16, 3.16.1, 3.17, 3.17.1, 3.18, 3.19, 3.19.1
Change logNone available
Dependenciesarray, base (>=2.0 && <5), containers, directory, ghc, ghc-paths, haskeline, haskell98, mtl, parsec [details]
AuthorJustin Ethier
MaintainerJustin Ethier <>
CategoryCompilers/Interpreters, Language
Home page
UploadedFri Jun 3 00:39:16 UTC 2011 by JustinEthier
Downloads7840 total (235 in last 30 days)
0 []
StatusDocs not available [build log]
All reported builds failed as of 2015-11-21 [all 5 reports]



Maintainers' corner

For package maintainers and hackage trustees

Readme for husk-scheme-3.0

husk Scheme

husk is a dialect of Scheme written in Haskell that implements a subset of the R<sup>5</sup>RS standard. Advanced R<sup>5</sup>RS features are provided including continuations, hygienic macros, and a full numeric tower.

husk provides many features and is intended as a good choice for non-performance critical applications, as it is not a highly optimized Scheme. Rather, the goal of the project is to provide a tight integration between Haskell and Scheme while at the same time providing an opportunity for deeper understanding of both languages. In addition, 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.

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 the 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.

Feature List

husk includes the following features from R<sup>5</sup>RS:

As well as the following approved extensions:

husk scheme is available under the MIT license.


husk may be easily installed using cabal - just run the following command:

cabal install husk-scheme


The interpreter may be invoked by running it directly from the command line:


Alternatively, you may run an individual scheme program:

./huski my-scheme-file.scm


A Haskell API is also provided to allow you to embed a Scheme interpreter within a Haskell program. The key API modules are:

For more information, run make doc to generate API documentation from the source code. Also, see shell.hs for a quick example of how you might get started.

Foreign Function Interface

A foreign function interface (FFI) is provided to allow husk to call into arbitrary Haskell code. The interface is currently available via the load-ffi function:

(load-ffi "Language.Scheme.Plugins.CPUTime" "precision" "cpu-time:precision")

load-ffi accepts the following string arguments:

From the previous example, once cpu-time:precision is loaded, it may be called directly from husk just like a regular Scheme function:


Any Haskell function loaded via the FFI must be of the following type:

[LispVal] -> IOThrowsError LispVal

See husk's Language.Scheme.Plugins.CPUTime module for an example of how to use the husk FFI.


The following packages are required to build husk scheme:

The scm-unit-tests directory contains unit tests for much of the scheme code. All tests may be executed via make test command.

The examples directory contains example scheme programs.

Patches are welcome; please send via pull request on github.


husk scheme is developed by Justin Ethier.

The interpreter is based on code from the book Write Yourself a Scheme in 48 Hours written by Jonathan Tang and hosted / maintained by Wikibooks.

If you would like to request changes, report bug fixes, or contact me, visit the project web site at GitHub.