functor Make(M : sig type data val inj : sql_injectable data end) = struct type ref = int sequence s table t : { Id : int, Data : M.data } fun new d = id <- nextval s; dml (INSERT INTO t (Id, Data) VALUES ({[id]}, {[d]})); return id fun read r = o <- oneOrNoRows (SELECT t.Data FROM t WHERE t.Id = {[r]}); case o of None => error You already deleted that ref! | Some r => return r.T.Data fun write r d = dml (UPDATE t SET Data = {[d]} WHERE Id = {[r]}) fun delete r = dml (DELETE FROM t WHERE Id = {[r]}) end