[Hs-Generics] patch applied (generics): Fix Derive.hs to avoid recursion in Data instances

[Alexey Rodriguez Yakushev]

Tue Apr  1 06:00:26 PDT 2008  Alexey Rodriguez <mrchebas at gmail.com>
  * Fix Derive.hs to avoid recursion in Data instances
  
  * We only make context for type variables
    otherwise it generates contexts such as:
   
      instance (Data ctx a,Data ctx [a],...) =>
         Data ctx [a] where ...
   
    rather than
    
      instance (Data ctx a,...) =>
         Data ctx [a] where ...
   
  

    M ./comparison/syb3/Derive.hs -1 +25