View on GitHub

IHaskell: Haskell for IPython

A Haskell language backend for IPython interactive shell and notebook.

Download this project as a .zip file Download this project as a tar.gz file

IHaskell

IHaskell

IHaskell is an implementation of the IPython kernel protocol which allows you to use Haskell inside IPython frontends such as qtconsole and notebook.

The project works with the IPython shell:

IPython Console

As well as the IPython browser-based notebook interface:

IPython Notebook

More usage information on the wiki.

Installation

ZeroMQ

IHaskell uses a library known as ZeroMQ for asynchronous communication. Make sure that ZeroMQ 4 is installed - it is a relatively recent library and thus you may have older versions installed.

For Macs, you can easily install it with Homebrew:

# For Macs with Homebrew:
brew update
brew install zeromq

On other platforms, you can easily install from source:

# Compiling from source:
git clone git@github.com:zeromq/zeromq4-x.git libzmq
cd libzmq
./autogen.sh && ./configure && make
sudo make install
sudo ldconfig

If your own platform has a package and I haven't included instructions for it, feel free to send me an email or a PR on this README.

Haskell and Cabal

You should also have GHC and modern Cabal:

ghc --numeric-version # Should be 7.6.3
cabal --version       # Should be 1.18.*

Since IHaskell uses the GHC API for evaluation and parsing, other versions of GHC may not work.

If you do not have GHC or Cabal, you should be able to install both via the Haskell Platform. On Macs with Homebrew, you can do this via

# Macs with Homebrew only, if you don't have GHC or Cabal
brew install haskell-platform
cabal update && cabal install cabal-install

Use cabal install cabal-install to update Cabal if you still have version 1.16 instead of 1.18.

Also, in order to use executables which cabal installs, they must be in your path. Execute this in your shell or add it to your ~/.bashrc:

# If you have a ~/.cabal/bin folder:
export PATH=~/.cabal/bin:$PATH

# If you have a ~/Library/Haskell/bin folder on OS X:
export PATH=~/Library/Haskell/bin:$PATH

Compilation Tools

Install the happy parser generator tool and cpphs preprocessor:

cabal install happy cpphs

IHaskell Installation

Install the IHaskell package from Hackage:

cabal install ihaskell

Running IHaskell

Finally, run the notebook or console interface:

IHaskell notebook # Should open a browser window!
IHaskell console

There is a test notebook in the IHaskell directory. To try it, run IHaskell with IHaskell notebook --serve=IHaskell.

Note: You may have some trouble due to browser caches with the notebook interface if you also use IPython's notebook interface or have used it in the past. If something doesn't work or IPython says it can't connect to the notebook server, make sure to clear the browser cache in whatever browser you're using, or try another browser.

Contributing

IHaskell is a young project, and I'd love your help getting it to a stable and useful point. There's a lot to do, and if you'd like to contribute, feel free to get in touch with me via my email at andrew period gibiansky at gmail - although browsing the code should be enough to get you started, I'm more than happy to answer any questions myself.

For package maintainers: IHaskell has an ability to display data types it knows about with a rich format based on images or HTML. In order to do so, an external package ihaskell-something must be created and installed. Writing these packages is simply - they must just contain instance of the IHaskellDisplay typeclass, defined in IHaskell.Display, and for a package ihaskell-something should have a single module IHaskell.Display.Something. If you have a package with interesting data types that would benefit from a rich display format, please get in contact with me (andrew dot gibiansky at gmail) to write one of these packages! A sample package is available here.

Developer Notes

Before diving in, you should read the brief description of IPython kernel architectures and read the complete messaging protocol specification.

Skim the rather-lacking Haddock documentation.

Module Quickstart:

First steps:

cd /path/to/IHaskell
cabal configure --enable-tests
cabal build

Loading IHaskell into GHCi for testing:

Use one of the methods below to access IHaskell files in GHCi. Once inside GHCi, you can load an IHaskell file; for example, :load IHaskell/Config.hs.

Using cabal repl

If you have the latest version of cabal (>v1.18.0), the simplest thing to do is

cd <path-to-IHaskell>
cabal repl

The will hide all packages not listed in the IHaskell.cabal

Using GHCi directly

If you don't want to use cabal repl, you can just call ghci which can read the .ghci file included in the repository for the options.

cd <path-to-IHaskell>
chmod 600 .ghci # trust the .ghci file
ghci

Then in the ghci session you can type things like:

:load src/Hspec.hs
hspec parserTests
:browse IHaskell.Types