[Haskell] Program maintenance tools

Hello I'm looking for some tools to help maintain a largish Haskell program. Some of the things I'd like tool support for are: - detection of dead code; - detection of unnecessary arguments for functions; - detection of unnecesary imports of modules; - a graphical representation of dependencies between modules. Any pointers would be much appreciated. Gavin -- Gavin Lowe Oxford University Computing Laboratory, Parks Road, Oxford, OX1 3QD. Phone: +44 1865 273841. Fax: +44 1865 273839. E-mail: gavin.lowe@comlab.ox.ac.uk The secret of all discoverers is that they regard nothing as impossible