Right now I'm spending some time on exploring how haskell could be used to model a small in memory only RDBM system. (Final goal is to use it with HAppS state etc..) A db description looks like this: $(let cds = defaultTable { tblName = "cds" , columns = [ ("cdId", conT ''Int) , ("title", conT ''Int) ] , primary = PrimaryUniq [ "cdId" ] (MaxPKPlusOne 10) , indexes = [ Index "title" [] ] , tblStates = [ ( "nextCdId", [t| Int |], [| 0 |] ) ] } tracks = let a="a" in defaultTable { tblName = "tracks" , columns = [ ("trackId", conT ''Int ) , ("name", conT ''String) , ("cd", conT ''Int) -- foreign key ] , primary = PrimaryUniq [ "cd", "trackId" ] -- is there a nice way than using that many mkNameE (SetSubPKPlusOne 5) , indexes = [ Index "cd" [ IndexUnique "trackId" ] ] --the id is uniq foreach cd -- checks = [ foreignConstraint "cd" "cds" "id" ] -- triggers = [ InsertUpdate (Just ["cd"]) [| cdUpdateByPK ( updateNum_tracks (+1) ) . pk |] -- DeleteUpdate (Just ["cd"]) [| cdUpdateByPK ( updateNum_tracks (-1) ) . pk |] -- ] } db = defaultDB { dbName = "my" , tables = [ cds, tracks] , statistics = True } in createDB db) instead of the MaxPKPlusOne you can also use your custom function to get the next primary id: [| \row -> withNextIdStateFromCds $ do s <- get; put (s+1); return s |] This will get more complicated for sofisticated use cases SetSubPKPlusOne. The primary key is made up of the cdId and the trackId. Now I'd like to set the trackId to the smallest not yet used number. This results in something like row -> let cd = cdId row in let map = lookup cd (get index map here) in if null map then 1 else (+1).fst.findMAx map which is fine except that cdId and (get index map here) must use functions defined by createDB. So the only way to write this is cluttering everything up with $(varE $ mkName $ "cdId") which makes the code less readable.. So my question is: Would it make sense to ask ghc to take an unkown function, but instead of complaining rewrite it as varE $ mkName $ <name> ? Maybe one easy solution to achievie this is make haskell-src output an template haskell AST? Then you can get nice looking and readable code and still have most of the power of weriting template haskell ? Anyone thought about this? Mmh still thinking about how the query language should look like. I have something like printf syntax in mind... $(query "id > ?1 AND ?2 == text ") 7 "text" .. Marc Weber