"~{alias}" -> case (FS.f_value fjm >>= PP.fromPathPiece) of 
                    (Just v') -> where_ $ defaultFilterOp (FS.f_negate fjm) (FS.f_comparison fjm) (~{vn} ~{projectField isMaybe} ~{entityFieldTypeName e f}) (~{makeJust maybeLevel "(val v')"})
                    _        -> return ()