haskell list pacakges and install missing packages

You may want to install some additional haskell packages, where this page : http://www.haskell.org/ghc/distribution_packages has listed the packages for different distribution. 

let's take the Ubuntu desktop for example, where you can try to install with the following guideline. 

--if you find some package is missing, such as mtl, you may do the following to install the haskell pacakge. 

--   apt-cache search libghc6-mtl
-- and it shall shows some packages as follow
--      ligghc6-mtl-dev
--      ligghc6-mtl-doc
--      ligghc6-mtl-prof
-- then you shall be running the following command to install the pkg
--   apt-get install libghc6-mtl-dev