Learn you a Haskell for Great Good!
Glasgow Haskell compiler
Ubuntu has ghc6 packages in its universe repository.
Enable the unvierse repository in Synaptics, and then install the
ghc6, ghc6-prof and ghc-doc packages.
The extralibs, as well as various other libraries, are available as libghc6-library-dev. You may also want libghc6-library-prof and libghc6-library-doc for the profiling libraries and documentation respectively, but sometimes this will be included in the main package. You can also get the library sources in the ghc6-libsrc package.
Alternativesly, you can install from the command line: use apt-get update && apt-get install ghc6 ghc6-prof ghc6-doc to install GHC.