table tab : {Id : int, Val : int} PRIMARY KEY Id
fun cache id =
res <- oneOrNoRows (SELECT tab.Val
FROM tab
WHERE tab.Id = {[id]});
return
Reading {[id]}.
{case res of
None => ?
| Some row => {[row.Tab.Val]}}
fun flush id =
res <- oneOrNoRows (SELECT tab.Val
FROM tab
WHERE tab.Id = {[id]});
(case res of
None => return () (* dml (INSERT INTO tab (Id, Val) *)
(* VALUES ({[id]}, 0)) *)
| Some row => dml (UPDATE tab
SET Val = {[row.Tab.Val + 1]}
WHERE Id = {[id + 1]} OR Id = {[id]} (* OR Id = {[id - 1]} *)));
return
{case res of
None => Initialized {[id]}!
| Some row => Incremented {[id]}!}
(* task periodic 5 = *)
(* fn () => *)
(* t <- now; *)
(* let *)
(* val n = toSeconds t % 2 *)
(* in *)
(* dml (UPDATE tab *)
(* SET Val = 9001 *)
(* WHERE Id = {[n]} OR Id = {[n+1]}) *)
(* end *)