ziv@2213: table tab : {Id : int, Val : int} PRIMARY KEY Id
ziv@2203:
ziv@2213: fun cache id =
ziv@2225: res <- oneOrNoRows (SELECT tab.Val
ziv@2225: FROM tab
ziv@2225: WHERE tab.Id = {[id]});
ziv@2204: return
ziv@2213: Reading {[id]}.
ziv@2204: {case res of
ziv@2213: None => ?
ziv@2213: | Some row => {[row.Tab.Val]}}
ziv@2204:
ziv@2203:
ziv@2213: fun flush id =
ziv@2225: res <- oneOrNoRows (SELECT tab.Val
ziv@2225: FROM tab
ziv@2225: WHERE tab.Id = {[id]});
ziv@2221: (case res of
ziv@2234: None => return () (* dml (INSERT INTO tab (Id, Val) *)
ziv@2234: (* VALUES ({[id]}, 0)) *)
ziv@2225: | Some row => dml (UPDATE tab
ziv@2225: SET Val = {[row.Tab.Val + 1]}
ziv@2234: WHERE Id = {[id + 1]} OR Id = {[id]} (* OR Id = {[id - 1]} *)));
ziv@2204: return
ziv@2204: {case res of
ziv@2213: None => Initialized {[id]}!
ziv@2213: | Some row => Incremented {[id]}!}
ziv@2204:
ziv@2234:
ziv@2234: (* task periodic 5 = *)
ziv@2234: (* fn () => *)
ziv@2234: (* t <- now; *)
ziv@2234: (* let *)
ziv@2234: (* val n = toSeconds t % 2 *)
ziv@2234: (* in *)
ziv@2234: (* dml (UPDATE tab *)
ziv@2234: (* SET Val = 9001 *)
ziv@2234: (* WHERE Id = {[n]} OR Id = {[n+1]}) *)
ziv@2234: (* end *)