Hi all, I have below duplicate code, but i don't know how to use TH instance code. ------------------------------> duplicate code start <------------------------------ instance Variable PageType where toVariant = toVariant . show fromVariant x = fmap (\v -> read v :: PageType) $ fromVariant x instance Variable Int where toVariant = toVariant . show fromVariant x = fmap (\v -> read v :: Int) $ fromVariant x instance Variable (Maybe Char) where toVariant = toVariant . show fromVariant x = fmap (\v -> read v :: Maybe Char) $ fromVariant x instance Variable (Maybe Int) where toVariant = toVariant . show fromVariant x = fmap (\v -> read v :: Maybe Int) $ fromVariant x instance Variable ProcessID where toVariant = toVariant . show fromVariant x = fmap (\v -> read v :: ProcessID) $ fromVariant x instance Variable GWindowId where toVariant = toVariant . show fromVariant x = fmap (\v -> read v :: GWindowId) $ fromVariant x ------------------------------> duplicate code end <------------------------------ Any TH expert help? Thanks, -- Andy