Student paper: HaskellDB improved

We present an improved version of the HaskellDB database library. The original version relied on TRex, a Haskell extension supported only by the Hugs interpreter. We have replaced the use of TRex by a record implementation which uses more commonly implemented Haskell extensions.Additionally, HaskellDB now supports two different cross-platform database backends. Other changes include database creation functionality, bounded string support, performance enhancements, fixes to the optimisation logic, transaction support and more fine grained expression types.