Hi In future questions like this are usually best directed to haskell-cafe, with haskell being left for annoucements. The standard "full haskell" representation is in Template Haskell (http://haskell.org/ghc/docs/latest/html/libraries/template-haskell/Language-...). If you want to work on a reduced language then I recommend Yhc.Core (http://www-users.cs.york.ac.uk/~ndm/yhc/ - there is a link to the Yhc.Core paper on that page). Thanks Neil