From: "Rene de Visser" test = [| add_rel1 value = modify (\db -> db{ rel1 = Set.insert value (rel1 db)}) |] {-# OPTIONS -fglasgow-exts #-} module DataBase where

import Control.Monad.State import qualified Data.Set as Set -- Does this really need to be extensible??? -- Entries need to be based on sets, or something similar... data SmallDB = SmallDB { rel1 :: Set.Set String , rel2 :: Set.Set Integer } deriving Show

emptyDB = SmallDB Set.empty Set.empty

add_rel1 :: (MonadState SmallDB m) => String -> m () add_rel1 value = modify (\db -> db{ rel1 = Set.insert value (rel1 db)})

add_rel2 :: (MonadState SmallDB m) => Integer -> m () add_rel2 value = modify (\db -> db{ rel2 = Set.insert value (rel2 db)})

So I've made a tiny bit of progress. I have: test9 = [d| add_rel1 value = $(exp) value |] where exp = [| (\value -> modify (\db -> $(updater) db (Set.insert value (rel1 db)))) |] where updater = [|(\db value -> db{rel1 = value}) |] --updater = LamE [VarP db_2,VarP value_3] (RecUpdE (VarE db_2) [(DataBase.rel1,VarE value_3)]) where db_2 = mkName "db_2" ; value_3 = mkName "value_3" However if I replace updater by its expansion, I get a type error. Why? It looks like an expansion of a quasi quote is not identical to the quasi quote? Rene.