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@2273: (* fun cache2 id v = *) ziv@2273: (* res <- oneOrNoRows (SELECT tab.Val *) ziv@2273: (* FROM tab *) ziv@2273: (* WHERE tab.Id = {[id]} AND tab.Val = {[v]}); *) ziv@2273: (* return *) ziv@2273: (* Reading {[id]}. *) ziv@2273: (* {case res of *) ziv@2273: (* None => Nope, that's not it. *) ziv@2273: (* | Some _ => Hooray! You guessed it!} *) ziv@2273: (* *) ziv@2273: ziv@2273: fun cache2 id1 id2 = ziv@2273: res1 <- oneOrNoRows (SELECT tab.Val ziv@2273: FROM tab ziv@2273: WHERE tab.Id = {[id1]}); ziv@2273: res2 <- oneOrNoRows (SELECT tab.Val ziv@2273: FROM tab ziv@2273: WHERE tab.Id = {[id2]}); ziv@2269: return ziv@2273: Reading {[id1]} and {[id2]}. ziv@2273: {case (res1, res2) of ziv@2273: (Some _, Some _) => Both are there. ziv@2273: | _ => One of them is missing.} ziv@2269: ziv@2269: ziv@2213: fun flush id = ziv@2239: dml (UPDATE tab ziv@2239: SET Val = Val * (Id + 2) / Val - 3 ziv@2239: WHERE Id = {[id]} OR Id = {[id - 1]} OR Id = {[id + 1]}); ziv@2204: return ziv@2235: Changed {[id]}! ziv@2204: ziv@2234: ziv@2242: val flush17 = ziv@2242: dml (UPDATE tab ziv@2242: SET Val = Val * (Id + 2) / Val - 3 ziv@2242: WHERE Id = 17); ziv@2242: return ziv@2242: Changed specifically 17! ziv@2242: ziv@2242: ziv@2235: (* fun flush id = *) ziv@2235: (* res <- oneOrNoRows (SELECT tab.Val *) ziv@2235: (* FROM tab *) ziv@2235: (* WHERE tab.Id = {[id]}); *) ziv@2235: (* (case res of *) ziv@2235: (* None => dml (INSERT INTO tab (Id, Val) *) ziv@2235: (* VALUES ({[id]}, 0)) *) ziv@2235: (* | Some row => dml (UPDATE tab *) ziv@2235: (* SET Val = {[row.Tab.Val + 1]} *) ziv@2235: (* WHERE Id = {[id]} OR Id = {[id + 1]})); *) ziv@2235: (* return *) ziv@2235: (* {case res of *) ziv@2235: (* None => Initialized {[id]}! *) ziv@2235: (* | Some row => Incremented {[id]}!} *) ziv@2235: (* *)