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 =
dml (UPDATE tab
SET Val = Val * (Id + 2) / Val - 3
WHERE Id = {[id]} OR Id = {[id - 1]} OR Id = {[id + 1]});
return
Changed {[id]}!
(* fun flush id = *)
(* res <- oneOrNoRows (SELECT tab.Val *)
(* FROM tab *)
(* WHERE tab.Id = {[id]}); *)
(* (case res of *)
(* None => dml (INSERT INTO tab (Id, Val) *)
(* VALUES ({[id]}, 0)) *)
(* | Some row => dml (UPDATE tab *)
(* SET Val = {[row.Tab.Val + 1]} *)
(* WHERE Id = {[id]} OR Id = {[id + 1]})); *)
(* return *)
(* {case res of *)
(* None => Initialized {[id]}! *)
(* | Some row => Incremented {[id]}!} *)
(* *)